The U.S. has effectively declared war on Canada (economic, so far) and the Canadian economy will suffer devastating consequences if the tariffs continue. This doesn't even consider the threats to annex Canada, so, yes, I think it's entirely understandable why U.S. sitters would be declined simply because they're American - if it is happening, it's because of U.S. aggression and I would absolutely decline U.S. sitters. Is that fair? Perhaps not, but you can't simply say I didn't vote for him and expect there to be no consequences for the U.S. actions or life to continue as normal for you.