he would still be free then to campaign against it on the basis of it being a tory deal?
No, campaign for it! Let the Tories take the credit now, the blame later if as predicted everything goes t**s up.
TBH I've always thought Jeremy's aim was to take Power, that he would not make the mistake of other left wingers and stand on the side-lines pulling faces. To be as ruthless (and disgusting) as Boris was in becoming PM. Brexit has gone, Boris's deal is the best we will get whilst the country remains split over Brexit. Boris has more or less silenced the ERG, shafted the DUP and may well restore the whip to at least 18 of the 21 rebels.
The Brexit battle has passed for Labour/Jeremy, but the Brexit peace is still to be won. Jeremy and his team need to be the ones negotiating the second phase on Trade matters, he can align his requirements on workers rights etc. because he will be PM and hopefully have a workable majority. Its the same with everything else via Brexit the control will be restored to Westminster and he and the Labour party need to be holding sway in that particular 'Palace' when it does.
When I was in my twenties I would have followed such as Jeremy to the ends of the earth. However as I grew older I realised that all these so called 'true Socialist leaders' were nothing of the kind, yes they espoused Socialism, were able to rouse a crowd, but had no idea how to lead. As I've got older I have become more Conservative (with a small 'c') and every other Labour Leader I've seen in my lifetime, were leaders, but not true socialists. Tories nearly always had good leaders and in fact all though I know I will get howled down for this, they have benefitted the working man more than Labour has and have been able to see off even hard cases like Arthur Scargill.
Tories know how to pick their battles and for once with Jeremy I thought Labour might (by accident i.e having his name added to list of leadership candidates, when he was unable to muster enough supporters) have got one who has not changed his political views and might turn out to be a leader AND A SOCIALIST!
TBH I'm not sure the 'Socialism' espoused nowadays is the one I hoped for in my youth, but before I pass over I would (secretly not even my close friends know this)) like to see one
real socialist have a go at the 'big job'. Forget Brexit Jeremy, "eyes on the prize lad".