Why is a middle aged man like Justin Trudeau portrayed as young?

Justin Trudeau at age 40 - 41 by the time of the Liberal leadership convention and 43 by the time of the 2015 federal election.   He is middle aged and not young to become the leader of a major political party in Canada.   If Trudeau were in his early 30s one could talk about him being young as a leader.  Being in your 40s and trying to be any part of a youth movement is really not becoming of a middle aged man, frankly it is a bit creepy.

He is roughly the same age Stephen Harper was when he took over the Canadian Alliance.  He is older already than Joe Clark as Prime Minister or Ed Broadbent as leader of the NDP.

Trudeau may have many reasons people may wish to support him to be Liberal leader, but being "young" is not one.

Below is a list of the age at which people became leaders of major parties in Canada and when they become Prime Minister or Premier.   When you look at the list below, becoming the leader of the number three party in the federal parliament at age 41 is not much of a youth accomplishment.

People have become leaders of major parties and lead governments at under the age of 40 since 1867 through to this last decade.  Premier Brad Wall was 38 when became leader of the Saskatchewan Party.

Bold signifies leader of a government, underlined is a federal politician, italics are for federal leaders that never formed a government, I chose 48 as the cut off because that was the age of Trudeau's father when he was sworn in.

30 - George King Premier of New Brunswick and leader of the New Brunswick Conservatives
31 - Bod Rae leader of the Ontario NDP
32 - Richard McBride BC Premier and leader of the Conservatives
32 - William Pipes Premier of Nova Scotia and leader of the Nova Scotia Liberals
32 - Bernard Lord leader of the New Brunswick PCs
32 - Louis Robichaud leader of the New Brunswick Liberals
33 - Ed Shreyer Premier of Manitoba and leader of the Manitoba NDP
33 - Bernard Lord Premier of New Brunswick
34 - Louis Robichaud Premier of New Brunswick
34 - Mitch Hepburn leader of the Ontario Liberals
34 - Shawn Graham leader of the New Brunswick Liberals
34 - Robert Stanfield leader of the Nova Scotia PCs
35 - George Murray Premier of Nova Scotia and leader of the Nova Scotia Liberals
35 - Joe Clark leader of the PCs
35 - Jean Charest leader of the PCs
35 - Grant Devine leader of the Saskatchewan PCs
35 - Edward Blake leader of the Ontario Liberals
36 - Robert Bourassa Premier of Quebec and leader of the Quebec Liberals
36 - Rodney MacDonald Premier of Nova Scotia and leader of the Nova Scotia PCs
36 - John Thompson Premier of Nova Scotia and leader of the Nova Scotia Conservatives
36 - Brian Peckford Premier of Newfoundland and leader of the Newfoundland PCs
37 - Mitch Hepburn Ontario Premier 
37 - Grant Devine Premier of Saskatchewan 
37 - Thomas Scott Premier of Saskatchewan and leader of the Saskatchewan Liberals
37 - Peter Lougheed leader of the Alberta PCs
37 - Duff Roblin leader of the Manitoba PCs
37 - Gerald Regan leader of the Nova Scotia Liberals
37 - Frank McKenna leader of the New Brunswick Liberals
37 - Tommy Douglas leader of the Saskatchewan CCF
37 - Henri-Gustave Joly de Lotbinière leader of the Quebec Liberals
37 - Joseph-Adolphe Chapleau leader of the Quebec Conservatives
38 - Edward Blake Premier of Ontario
38 - Walter Weir Manitoba Premier and leader of the Manitoba PCs
38 - Joseph-Adolphe Chapleau Premier of Quebec
38 - Frank Moores Premier of Newfoundland and leader of the Newfoundland PCs
38 - Shawn Graham Premier of New Brunswick
38 - Andrew Blair Premier of New Brunswick and leader of the New Brunswick Liberals
38 - Richard Hatfield leader of the New Brunswick PCs
38 - John Douglas Hazen leader of the New Brunswick Conservatives
38 - Brad Wall leader of the Saskatchewan Party
38 - David Peterson leader of the Ontario Liberals
39 - Joe Clark Prime Minister
39 - Glen Clark Premier of BC and leader of the BC NDP
39 - Frank McKenna Premier of New Brunswick 
39 - Richard Hatfield Premier of New Brunswick
39 - Gédéon Ouimet Premier of Quebec and leader of the Quebec Conservatives
39 - Fredrick Haultain Premier of NWT (which really meant Alberta and Saskatchewan)
39 - Tommy Douglas Premier of Saskatchewan 
39 - John Braken Premier of Manitoba and leader of the United Farmers of Manitoba
39 - Pierre-Marc Johnson Premier of Quebec and leader of the PQ
39- Dave Barrett leader of the BC NDP
39 - John Buchanan leader of the Nova Scotia PCs
39 - Simon Holmes leader of the Nova Scotia Conservatives
39 - Gary Doer leader Manitoba NDP (premier at age 51)
39 - Ed Broadbent leader of the NDP
40 - Jean Charest leader of the Quebec Liberals
40 - Angus Macdonald leader of the Nova Scotia Liberals
41 - David Peterson Premier of Ontario
41 - Ernest Drury Premier of Ontario and leader of the United Farmers of Ontario
41 - Bill Davis Ontario Premier and leader of the Ontario PCs
41 - Brad Wall Premier of Saskatchewan 
41 - Dave Barrett Premier of BC
41 - Brian Tobin Premier of Newfoundland and leader of the Newfoundland Liberals
41 - Gary Filmon leader of the Manitoba PCs
41 - Bill Bennett leader of BC Social Credit
42 - Bob Rae Premier of Ontario
42 - Robert Stanfield Premier of Nova Scotia
42 - Ernest Manning Premier of Alberta and leader of the Alberta Social Credit
42 - John Brownlee Alberta Premier and leader of the United Farmers of Alberta
42 - Gerald Regan Premier of Nova Scotia
42 - James Gardiner Premier of Saskatchewan and leader of the Saskatchewan Liberals
42 - Clifford Robinson Premier of New Brunswick and leader of the New Brunswick Liberals
42 - Stephen Harper leader of the CA
42 - Ross Thatcher leader of the Saskatchewan Liberals
42 - Harlen Brewster leader of the BC Liberals
43 - Bill Bennett BC Premier
43 - Walter Foster Premier of New Brunswick and leader of the New Brunswick Liberals
43 - Duff Roblin Premier of Manioba
43 - Angus Macdonald Premier of Nova Scotia 
43 - Peter Loughheed Alberta Premier
43 - Adélard Godbout Premier of Quebec and leader of the Quebec Liberals
43 - Camille Thériault Premier of New Brunswick and leader of the New Brunswick Liberals
43 - Rodmond Roblin leader of the Manitoba Conservatives
43 - Honore Mercier leader of the Quebec Liberals
43- Maurice Duplessis leader of the Quebec Conservatives
44 - Mackenzie King leader of the Liberals
44- Stuart Garson Premier of Manitoba and leader of the Manitoba Liberals
44- Jean Charest Premier of Quebec
44 - Donald Cameron Premier of Nova Scotia and leader of the Nova Scotia PCs
44- Henry Emmerson Premier of New Brunswick and leader of the New Brunswick Liberals
44 - Lomer Gouin Premier of Quebec and leader of the Quebec Liberals
44 - Brian Mulroney leader of the PCs
44 - Allan Blakeney leader of the Saskatchewan NDP 
44 - George Drew leader of the Ontario PCs
44 - Howard Pawley leader of the Manitoba NDP
44- Thomas Crerar leader of the Progressives 
44 - Solon Low leader of Social Credit
45 - Brian Mulroney Prime Minister
45 - Christy Clark BC Premier and leader of the BC Liberals
45 - Joseph-Alfred Mouseau Premier of Quebec and leader of the Quebec Conservatives
45 - Simon-Napoléon Parent Premier of Quebec and leader of the Quebec Liberals
45 - Allan Blakeney Premier of Saskatchewan
45 - William Fielding Premier of Nova Scotia and leader of the Nova Scotia Liberals
45 - Gary Filmon Premier of Manitoba 
45 - Preston Manning leader of the Reform Party (51 when elected as MP)
45 - John Horne Blackmore leader of Social Credit
45 - Michel Gauthier leader of the Bloc Quebecois
46 - Kim Campbell Prime Minister and leader of the PCs
46 - Stephen Harper Prime Minister
46 - Arthur Meighen Prime Minister and leader of the Conservatives
46 - Charles Dunning Premier of Saskatchewan and leader of the Saskatchewan Liberals
46 - Harlen Brewster BC Premier 
46- Louis-Olivier Taillon Premier of Quebec and leader of the Quebec Conservatives
46- Honore Mercier Premier of Quebec
46 - Maurice Duplessis Premier of Quebec
46 - Alison Redford Alberta Premier and leader of the Alberta PCs
46 - Ross Thatcher Premier of Saskatchewan 
46 - Réal Caouette leader of the Ralliement des créditistes
47 - Mackenzie King Prime Minister
47 - John Thompson Prime Minister and leader of the Conservatives
47 - George Drew Ontario Premier
47 - Pierre-Joseph-Olivier Chauveau Quebec Premier and leader of the Quebec Conservatives
47 - Russell McLellan Premier of Nova Scotia and leader of the Nova Scotia Liberals
47 - Andrew Wetmore Premier of New Brunswick and leader of the New Brunswick Conservatives
47 - Rodmond Roblin Premier of Manitoba
47 - John Buchanan Premier of Nova Scotia
47 - Simon Holmes Premier of Nova Scotia 
47 - Hiram Blanchard Premier of Nova Scotia and leader of the Nova Scotia Conservatives
47 - Gordon Harrington Premier of Nova Scotia and leader of the Nova Scotia Conservatives 
47 - John Douglas Hazen Premier of New Brunswick 
47 - Robert Thompson leader of Social Credit
48 - Pierre Trudeau Prime Minister and leader of the Liberals
48 - Henri-Gustave Joly de Lotbinière Premier of Quebec
48 - Harry Nixon Ontario Premier
48 - Edgar Rhodes Nova Scotia Premier and leader of the Nova Scotia Conservatives
48 - William Martin Premier of Manitoba and leader of the Saskatchewan Liberals
48 - Howard Pawley Premier of Manitoba
48 - Woodrow Lloyd Premier of Saskatchewan and leader of the Saskatchewan NDP
48 - Joey Smallwood Premier of Newfoundland leader of the Newfoundland Liberals