I think there's a few things going on here:
- surveys are just bad, you have a selection bias right off the bat, especially from an outfit like the globe and mail
- the idea is that an invasion would be overwhelming and futile to resist. Russia is not going to invade Canada. I think the assumption would be it'd be China (also very unrealistic) or the USA (this used to be unrealistic).
Given an unavoidable end result, I can kind of understand the idea that you wouldn't want to die for that. Plus there's the idea it'd be a soft invasion, where life would be good after. If Canadians had to fight for their actual lives, I would hope you'd see a bit more resistance. But that's the issue when you have a barely functional military, you can't just make one overnight.
There's already a good number of folks who would like a US annexation (in theory at least), as you allude to.
The cultural aspects are a little more complicated than what you describe, but I'll leave that.
