Sorry to go all patriarchy here, but the little Schneier on my shoulder just explained to me how to get anyone's talk cancelled at a conference that institutes this sort of policy.
I'm not sure that's a workable fix, either. This is sort of a hard problem.
Judging from the organizer's response there was little doubt concerning the validity of her claims in this case though.
In other cases, pulling said person into a room, asking him if the claims are true and if so asking them to leave is already a big step forward.
I doubt anything but praise would have resulted from that, even though the best outcome would be that it was kept private and became a little piece of background gossip floating around the Django-community.