There seems to be a big misunderstanding here about what a post-VoNC Government of National Unity would be there to do, and how long it would last. The whole point of a cobbled together GoNU would be to : 1) prevent crashing out on Oct 31 by 2) requesting an extension from the EU and 3) set up a GE to ascertain who would form the next government.
That's it, and so consequently a GoNU would not need to last for very long - a few weeks at most, and would not confer any significant powers on whomever ends up leading it. Letting Corbyn be in charge - IF that is required - would not be 'giving him the keys'. It would at best be lending him the keys so he can go and do one or two specific things, before handing them back.
The idea that a GoNU would set up a new referendum or revoke A50 is fanciful. I mean I would love either to happen, and particularly the latter, but the chances are minute, so forget it.
It'll purely be about preventing a cynical Johnsonian crash out and instigating a GE. So really it doesn't matter who is 'leader' as long as the bloody thing can be cobbled together against all the odds. Consequently the likelihood is that the other parties, and most here, would be best off biting their tongues and letting Corbyn have the role, if that means bringing the whole Labour Party (absent the handful of usual suspects) to the project and makes a GoNU happen. Any purism from the Lib Dems or whoever that results in a refusal to let Corbyn lead, if that ends up being what is needed, would literally be enabling a NO Deal crash out. In that regard TheShankleyGates is correct.
Don't get me wrong, I really hope a GoNU can be cobbled together with a respected neutral figure, or a Remainer, in charge. But if, as is looking likely, the numbers and intransigence of Labour require Corbyn to lead, then I'd have no hesitation in endorsing that. He'd have no powers anyway, and only be charge for a pre-agreed, limited time.
It would literally be cutting your nose off to spite your face for any Remainer to think otherwise. A no-deal crash out is the only alternative
Of course Tory intransigence as to joining a GoNU led by Corbyn, probably means the numbers won't work for him either, so it is probably a non-issue. But this post is just about the principle.