TL;DR they think he should look at electoral reform again
A huge wedge of the liberal voter base were disenfranchised when Trudeau promised electoral reform, practically guaranteed it, and then just announced they weren't going to do it but don't worry here's legal weed. Many of them were youth voting for the first time, and that betrayal set the tone. If he set it in motion before the election, is it possible they'd recapture at least some of that base? Sure. Would I vote for him? Not a chance.