I assume he's going to fuck off being an MP at some point soon anyway. Why would he want to sit there all day in a room full of people who hate his guts?
I suppose it'll come down to what motivates him the most out of spite, laziness or greed.
As a back bencher he doesn’t actually have to do anything if he doesn’t want to. Just sit back and collect the salary.
At the same time he’s freed up to go back to lucrative newspaper columns, etc that had to give up when became minister.
And from his point of view the most important thing now is that the next PM must fail.
To prove the party was wrong to dump him. That Johnson had the special touch to reach parts of the electorate others can’t. Whether that’s just to secure this note in the history books or possibly open things for his glorious return.
Sniping from the bank benches, rebelling against the government whip, causing all the shit he did for May’s government - back bench MP is the place he wants to be for that and to bring Sunak or whoever down.