It's less ambiguous. It's the name of the country. It's not a weird dunk to acknowledge that "America" is two continents (and that one them is in fact not called "Mexico"). What's weird is someone who lives in a country called USA being so insecure about being called USAn.
Europeans love to think when people say America they are referring to the continent, despite everyone knowing they mean the USA. I think it's an inferiority complex/dislike of US thing
Please refer to us with our chosen demonym, it’s just basic manners.
I could dunk on Germans by referring to them as Nazis then acting indignant when they protest, but I won’t, because that would be bizarre and make me look insane