He plainly feels that the internal issues caused by suspending Corbyn are worth suffering if it gives the party a better chance of power.
Is he right ? Havn't a clue to be honest, but, rightly or wrongly, Corbyn was seen as toxic by enough of the electorate to make a difference last time out, but whether that memory would linger long enough to make a difference next time out I doubt.
For years, before he was leader, Jeremy was a thorn in the flesh for many leaders, which was part of the reason he didn't get the support from the PLP that he should have done, but it's different poking the fire when you're just a backbencher as to when you're the previous leader. He knew this, but did it anyway.
It's very harsh on him, and probably isn't morally right , but , outside the confines of his own supporters, very few people will care if he's sacrificed by Starmer to make a point. It's a tough old world, but there you go, I won't be shedding any tears over it.