You might be making more of it than is really there. I remember Reagan was a popular with many Canadians. Then of course there were liberal Canadians that cursed him.I doubt it. I think it is more of a vicarious symbolic representation of their political views. Or in the case of Trump... just plain Cult Worshippers.
Canada's interest in U.S. politics would seem to have a lot to do with 90% of Canadians living near the U.S. border. Of course, the inverse isn't even close to being true. I don't know how Canadian television is structured, but I was under the impression most Canadians can watch American news. Other than on-line sources, I have no access to Canadian news.