I didn't read that LFS?   I would say No it's not ok to physically attack such a person in any situation outside of self protection or a threat to family.     In those situations, a reaction is almost impossible to control.    

I would suppose if I were a black male listening to a white supremacist spouting crude threats against all black, that I might feel more personally threatened?   I would hope words alone don't lead to violence, but I've seen fist thrown when one person goes over the line verbally.