Ah, I looked it up and you are right, he wasn't a sitting MP.
Yes, McGuinty is so damaged that he wouldn't even be elected as mayor of Dog River Sask, let alone a big city. That is why I find it laughable that posters are thinking he will try for a federal liberal leadership bid
the first day that he'd announce his intention and by the end of the day he'd get such a backlash that he'd withdraw