He waits til after No Deal to neuter the Brexit Party. He has kept to his word and got us out by Oct 31st. Didn't back down, etc etc etc.
He'd be gambling on anti-Corbyn feeling outweighing people pissed off about No Deal.
Realistically, once Brexit happens, where will Remain voters who are not natural Corbynites go? The Lib Dems are pushing themselves as the Stop Brexit party, but as far as I can see they don't have any story after that.