“if someone was constantly burnt by blacks” and put a sign on their shop “No Business with Blacks at this Establishment” I think YOU’d be the first to condemn them — regardless of the circumstances that led to that policy.
Either way, refusing to do business with blacks or religious Jews is a blatant violation of the anti-discrimination laws in all 50 states. I’m shocked you — who constantly are preaching rule of secular law here and dina d’malchusa — would not only tolerate it against YOUR OWN BRETHREN — but would use such racist pigs as an example.