He doesn't care. Go be in one. The rest of us have to make nice and professional and do our part to keep everything together while our ass is on the line. After the show, however, to paraphrase the Great Mr. Lynott, the drink may flow and blood may spill. As cathartic as casual violence can be, that's no reason not to be professional while the music's happening.
Folks are paying their money, they deserve a show.
So do the damn show, sing as best you can in the shitty monitors, then come offstage, drink four beers real fast, and jump on the offending engineer from behind. If you can't stay on for eight seconds, you're a wuss. It's very true of this life at any point on the ladder. Whether you're headlining at Ozzfest or paying to play at the worst local dive, there are always tremendous gaping stretches with nothing else to do. So when you're in Van Zone, or the soundcheck has become an epoch, or you're tired of playing pinball, do yourself a favor.