There is an implicit binary choice here, so “whether” fits. Both work, although I, for one, prefer to use “whether” for binary choices and “if” when there are more options. This is similar to my preference for “between” only for two things and “among” for more than two.
False syllogism (you speak Chinese, so you’re an asshole) or maybe premature generalization (some Chinese speakers are assholes, therefore all Chinese speakers are assholes).