Is it possible that he's letting it go to a vote because not so doing would necessitate his calling in the moving vans?
No, it's because when you are sure of victory in a democratic vote, why put it through yourself?
"Is it possible that he's letting it go to a vote because not so doing would necessitate his calling in the moving vans?"
If he's got enough votes to win (which he does), then there wouldn't be nearly enough support for any challenge to him as a result of not holding a vote.
He's only got a year and a bit left anyway, at best guess. The ongoing police investigations into donations to the Labour Party are more likely to make it shorter than anything else.