Dawkins I think has fallen victim to a common celebrity phenomenon, allowing himself to pander to the self-righteously spiteful among his audience. Hate is a powerful force for group cohesion, sadly more powerful than any of the positive emotions, and once the spark of "let's burn the witches!" takes hold, it's difficult to keep the fire from overpowering the core message.

That doesn't mean he should be excused for letting himself get where he is, of course. He should definitely be held accountable for it.