This thread pretty much gets the whole situation bang on, I think. Ultimately there's a small band of Remainers who, for some reason, think they're in a position to be calling the shots here when their power is, in actuality, fairly minimal.
If their claim to authority here is supposed to be that Corbyn's dangerous, or an anti-semite, or whatever else, then they automatically lose that claim to authority when you remember that any national unity government would still depend heavily on the support of...Corbyn! So they are willing to work with him...just only on their terms, with no compromise whatsoever. Even though Corbyn's the leader of the opposition here and therefore the one who holds the cards. Sure, we should expect him to compromise for the good of the country, but there's no reason for him to stand down purely because some Remainers don't like him when those Remainers, until now, have insisted stopping a No Deal Brexit comes above all else...only to now reverse their position because they don't actually want to work with Corbyn after all.