Canada is a big place, so unless they end up in the same city block as Dominion, there isn't much of story there.

There isn't anything that Canada (as a nation) gains out of this, so the motives are probably more petty and political. I think it is more likely that Trudeau wants to engage his base by thumbing his nose at America - they like it as long as it is anti-American. But that doesn't mean China wouldn't be ready to take advantage of it, and most likely with tacit Canadian consent. Having a contingent of CCP soldiers on Canada soil does open the door of deniability and tying up loose ends, just by numbers alone / remoteness of training - some can leave the training area and blend into Canadian society and do dirty work. But that would probably be too far removed from us common folks to ever get noticed.