I don't know that and neither do you. The optics would be really bad for someone who still has aspirations for the big job. I'm not judging his integrity, just saying it is also an astute political move. If Carney is as good as his word about expediting a bye election, it won't be long before he is back in the house.
We have seen a side of PP since the election was lost that we hadn't seen before. If he had shown it before, perhaps the conservatives wouldn't have lost. If he keeps it up, I wouldn't be surprised if he eventually does become PM.