I see, I always thought that the people running the event chose who went ahead and was able to run or not. I think I understand it now.Unless it's something super egregious, most often they are just warned once or twice.
The thing is, GDQ is paid for by the charities. They have the final say, and they do not want to be associated with anything hateful or seriously inappropriate.
(Edit) to be clear, the charities get 100% of the donations during the event, but the charities pay a fee for GDQ to run the events beforehand.