Someone who engages in political argument online isn't necessarily a "troll", that seems to be a convenient term to dismiss those one disapproves of.

He did engage in those in defense of anti-immigration views, which is not a crime, so far at least. Indications are that he, like a lot of Quebecers, was actually left-leaning in general, i.e. "liked" the NDP and Layton, as much as Trump and Le Pen. Those are not incompatible, particularly in Quebec.

NDP supporters were very disillusioned when Mulcair disavowed an anti-niqab stance and it cost him the election.

Since LAyton is dead, and so is the NDP in Quebec (and elsewhere), I doubt the NDP had any role whatsoever in this. Most likely it was Trudeau's stance on welcoming masses rejected by Trump, if anything.