In fairness though the US was still pretty butthurt about that whole WWII thing, we're pretty racist to middle easterners, maybe in fifty years people will look about at us and say we were racist. It's easy to call someone racist, less so when you've seen your friends get killed and/or tortured by a certain kind of person, you might find yourself a little prejudiced.
America is still racist to its own people, let alone the rest of the world. Most of the racial tensions shown on the internet all stem from American society.
I think, in a situation where someone is hitting you in the back of the head with the butt of a rifle, you should be entitled to call them whatever you want. Also, why is that guy hitting captain america in the back of the head with his gun rather than staying behind something he can't throw his shield through and firing all the bullets at him?