"He's a douchebag." Not that that means he can't be useful, but Howard just wants to put that out there. "He'd probably be our best bet, but no one knows where he went. And honestly, I'm not going to trust him not to screw us over, and not even the practical screwing people over thing that we do."

Diana and Howard are unlikely to get people killed out of pure malice. To better their odds at surviving, sure. But the Master is a different sort of evil.