The Blairites and Progress thought they'd won, they thought they had Labour on lockdown for the foreseeable and that those damn Militant lefties had been silenced for good.
The current situation is therefore wholly unacceptable to them. Because Labour shouldn't be about the membership, it shouldn't be about socialism, it shouldn't be for these Momentum upstarts. It should be for them, the sensible Moderates.
This won't end until the Labour Party is either back in power or split in two.
It should be about winning. Without power you cannot help people. If Corbyn gets Labour into power, great. If he doesn't, then it's time to change. Corbyn was given a massive boost by the Tory manifesto, without that dementia tax the needle wouldn't have moved and Labour would still be heading for a wipeout. I'm not convinced he is capable of winning an election against a competent Tory campaign. He's lucky that May's team shat the bed so badly.