E.g. he might be solely responsible for getting the Liberals reelected in Canada, something that a year ago you would have thought was absolutely impossible. But Trump is so deeply hated in Canada now that every time he mocks Trudeau it makes the Liberals more popular. Liberal support, which before Trump was elected was so low as to make a Conservative election win seem inevitable, has skyrocketed since Trump took office. It's now pretty much a dead heat, and that's before the Liberals have elected their new leader.
So I don't know, maybe he just really, really wanted the Liberals to get reelected and he pulled off the only way to make it happen. Maybe he felt sorry that Canadians seemed so internally divided, so he threatened to annex Canada to unite us.
Or maybe he's a moron that can't even understand cause and effect.