I'm not buying that older Canadians are any more informed about history, but putting that aside, maybe it's young Canadians self-interest. The article doesn't actually examine why they would want to join the US, but guesses at it being the consequence of "woke" policy. The pieces just aren't connected.

They may feel they have less to lose and more to potentially gain than older Canadians, who built up wealth and pensions in an economy that no longer exists. If they expect the country to offer worse pay, lifestyle, and services, disloyalty is not unreasonable. If a life in Canada means no home ownership, no healthcare or pensions in a few years, and that they won't be able to retire, that sounds a lot like the offer from the US. They're reasonably not sold on dying for Canadian oligarchs over American ones.