[Reach]

If you're worried about political statements at a charity event (which seems very reasonable), what worse way is there to go about it rather than simply asking politely for it to be removed (at which point banning for non compliance would make sense to everyone)?

Banning him attracts not only so much attention to the matter AND also gives republicans a reason to believe AGDQ staff were themselves making a political statement. Now they have to ban everyone that brings anything politically charged into the event, which seems very excessive, otherwise they won't appear to be impartial.