That's a fallacy, taking a stand against bigotry in no way makes you a bigot. There is a huge difference in refusing to support a person or a business on moral grounds than trying to copt the government of a nation to enforce bigoted believes. Trump is clearly advocating just that, using the the government to enforce anti-muslim restrictions.
I believe you've misused the word fallacy. Taking a stand against bigotry absolutely can make you a bigot. Different kinds of bigots engage in mutual opposition on a regular basis.
