I get that this Canadian as a 51st state is more talk than "serious" or w/e. But like so many of his craptastic ideas, this one is super craptastic. Trump may just completely hand the Liberals the PM singlehandedly.
There are a ton, I mean a ton of Canadians who hate Trudeau. Like hate hate him. But since he's not going to stay in that is getting defused a lot. The number of Canadians that actually want to be part of the US is like 0.0000001%. Of all my time up there, only one Canadian I ever came across ever semi-seriously entertained the thought (well before trump ever broached the idea) would rather have a separate Western Canada then actually join the US.
They conservatives up there very much want to be *like* certain things in America, but they very much want to just be Canadian, and not want anything to actually do with the US. Them joining the US would complete this very self-existential crisis of being completely overshadowed by the US. They know this and are hyper aware of it. It bothers them to even be confused as Americans, let alone join us. To even in jest suggest it before this created such a visceral reaction you'd not expect from a typically "polite" Canadian.
They also know how own government works, often better than we do. They know also just being 1 giant ass state would water them down so completely to be irrelevant. And also if they are conservative and already more or less upset they are more marginalized there, being just a state would do it more. Also probably not what trump thinks (duh), but they would probably elect 2 "democratic" /liberal senators, and probably would have majority be left leaning on the whole reps. That's assuming we even have democracy at that point so maybe worth retracting sadly.