It makes little sense to assign reactionaries to high level positions within your new left-wing party with the intent of purging them later. Also, as leader of the Labour Party he had the opportunity to purge the Blairite wing, but instead chose to work with them while they undermined him from the inside. There’s no reason to believe there will be purges.
I hope it’s because they intend to use the strategy of recruiting a lot and purging a lot
Yeah you’re right I’m way too optimistic sometimes