Nope. I think this is a stretch. It's what you put after "Americans are..." that determines the reaction. Saying that Canadians are "nice" or French people are moody isn't the same as saying Americans are racist, violent, etc. Even if they are. lol.

And it's not just Americans. Ask any POC, in any westernized country, to tell a white person that white people are a bunch of racists. I promise you, the reaction will be the same more often than not.