I’m sorry to hear that, especially regarding the change in status for the participant who had already received approval. I would ask you to please let them continue participating if possible, as I would hate to feel responsible for that decision being overturned. Your position is clear to me; I can only express my hope that you might reconsider this stance for future jam's.
Please don't feel responsible - this was a stance that we had been rethinking over the last few days irregardless; Your question just came during a time where it was most fitting for us to set our decision in stone.
We also hope that the other participant won't feel too bad about the change and we encouraged them to attempt to create something either way.