Yes, bigot is a slur, even when accurately applied.
Definition of bigot
: a person who is obstinately or intolerantly devoted to his or her own opinions and prejudices; especially : one who regards or treats the members of a group (such as a racial or ethnic group) with hatred and intolerance
Calling Trump a racist homophobe is a slur, and I'd stand by that too.
I would think it bigotry to label all JUB members as bigots, rather than the ones squealing with glee whenever given a chance to disparage blacks, muslims, regional populations, the poor, etc.
As I said from the time I joined this site over 10 years ago, it is no virtue to replace their hatred of a group of people with your hatred for a group of people. Hate actions. Hate government policies. Hate ignorance, but don't hate a people. When the world looks over, your angry face will look the same as the evil.
ANTIFA is the living proof that I was correct before it became a public fiasco.