Another reason why it is probably Toronto is that Canadians in general tend to think of one city as their 'home', or where they grew up. The fact that his sister doesn't question why he is in Toronto (only why he is at her house) makes me think that Toronto is their 'home' city, where both of them have lived for a long time.

He does have the attitude of a Toronto or Ontario dweller. Other areas of Canada have distinct little attitudes, especially in the west.