OP, you still haven't cleared up the question (in my mind anyway) what authority this guy has over the band. We know he plays guitar, runs sound, and is a childish bully. Is he the BL and everyone else is a hired gun? Besides running sound does he also provide the PA? Does he book all the gigs? Is he so valuable to the band that he can't be replaced? I understand some people do not like conflict and are willing to accept less than ideal situations to avoid problems with other people. Tapping your ruby red slippers together while wishing he'll behave next time is not a way to deal with this situation. He has no reason to behave next time. Unchallenged he'll only get worse. You identified a problem and he told you to STFU. When you tried to talk to him he stiff armed you. I say it's time you answer the bell.