A band has to be a family on some level. You can't have members bring blatantly disrespectful like that Brad guy sounds to be. The sound guy grabbing your managerial duties is truthfully no different than the singer grabbing the guitar out of the guitarists hands during a show. You are adults. Everyone knows what everyone else's job is. I would confront him 1 on 1. Tell him he needs to cut the crap. If he's that desperate for money, tell him to get a day job. This story seriously makes me angry.