If you negotiate a deal and then don't support what you negotiated why should you be trusted?
As you have also said, this is an intractable mess. I think that Labour agreeing a deal with the EU is possible, but I wouldn't care if they just put May's deal as the other option in a new referendum. That deal was scuppered by the ERG and DUP, so it must have something going for it. Corbyn is sensible to say he wouldn't campaign for one thing or the other in a new referendum, in case he has to implement whatever decision is made.
Whatever Corbyn says or does is automatically disparaged by most news outlets as far as I can tell. I've said it before, the idea that the current Labour front bench would do more damage to this country than the Tories and their enablers have done over the last 9 years is ridiculous. Corbyn might be a poor leader, but I'm not sure how we'd really know that, given he's spent most of his time in the role fending off attacks from the right-wing of his own party and faced relentless and mostly dishonest criticism from the Murdoch media and the BBC.
Personally, I'd prefer Corbyn to stand down and for Keir Starmer, or somebody else with less hostage-to-fortune history encumbering them, to stand unopposed, but if that's not going to happen, Labour are still the best hope. At least Corbyn seems to find it hard to be dishonest, unlike the current PM.
Well one argument for Brexit is that Remainers’ protests tend not to get violent.
I don't suppose you were serious, but the threat of violence from Leavers is no argument or justification for leaving. Pandering to thugs and bullies is never a good idea. Look where it got Theresa May.