Individuals joining is fine, that's what the immigration process is for. What I'm opposing is the indiscriminate admission of entire populations that do not align with Cansdian values.
For example, Minnesota barely passed some weak gun control legislation recently. How ready are they for the 2nd Amendment to be just gone? How keen would they be to have King Charles as their head of state? I think a lot of the people who say they're for joining Canada haven't considered all of the implications.
Minnesota does seem like one of the saner places in the US, but that's relative to the US.
Frankly, as a citizen of a formerly-allied country that the US is now openly discussing annexing by force, I'm fine with them crippling their military with absurd rules and standards. Go nuts, Hesgeth. Pile on the racism and sexism and whatever. Kick out any pilots or gunnery officers or whatever that are good at their jobs but that can't run a mile in whatever arbitrary time you pick. Ensure there are lots of well-trained former military personnel in your country that are bitter at your government but no longer under its control. I'm sure it'll go great.