As you've rightly said mate, he's an extremely unsuccessful MP candidate. He gets very little from running and losing again.
If you want my hunch, he wants to be on a national campaign gig, and free himself from the constrains (or rules) that govern electoral law in terms of constituency spending.
I think he will tour northern/midlands leave seats, diverting voters from tory to Brexit.
Where it's difficult for him, is he has to keep Brexit centrally in the news to have any chance, and begin to shift the idea that Johnson's deal is a sell out. Despite his rhetoric about winning Labour voters, it's clear he will win more ex and current tory voters on that basis.
Anyway whats your reading of it?