Even BEFORE the bit where he decided to sexually harass an audience member.
But, back when I first started moderating for WisCon I remember we got a cheat sheet with some useful phrases on it.
At the very bottom was, "can someone in the back please go get Safety?"
I am friends with LOTS of people who've been on the NYT best seller list who are LOVELY on panels!
When I've thought to set ground rules, people are almost always good about respecting them.
HOPEFULLY, if your con does panels well, the people on your panel will be some of the more-knowledgeable voices in the room.