This is utter nonsense. Unless there's some evidence of wrongdoing, pushing people out of your conference isn't acceptable. Especially if it's somebody with Crockford's reputation, who has influence, and both technical and social credit. This isn't an incident where people have come forward saying that somebody sexually or physically assulted them, and then they were banned (that's happened in some communities), it's somebody getting kicked from a conference for unknown reasons, when all the complaints about him boil down to, "some of the things he says can be rude or politically incorrect." That shouldn't be good enough. Especially if, like Crockford, the speaker has a reputation for providing valuable and relevant technical material.

Besides, if being rude was a reason to get banned from a conference, Linus, RMS, and countless others would have gotten lifetime bans from every conference out there years ago.