"Then why did they do it?" Because it's a newspaper, and newspapers pull stunts, and it sells extra copies and makes entertaining reading.

I think that in the Prof's joke about pretending to be Canadian, the implication is that that might be a good way for visitors to avoid feeling embarrassed, rather than to avoid getting harassed.

Generally people are predisposed to like Americans as people, even if they sometimes get tempted to tease them. That's nothing to do with thinking that your current administration is pretty unsavoury and incompetent. If people were really anti-American they'd want you to be landed with them for a few more years.

But don't worry about the letters from foaming at the mouth limey-haters - it won't get anyone hating Americans. It might encourage some unkind people to tease them, though, because that kind of reaction is such fun.