What makes you feel Canada is closer to the US than Europe? Remember, Canada is a European settler-colonial state. Its population descends mostly from European colonists. Its institutions, culture, commercial and industrial practices, etc. all come directly from European predecessors. Canada is an offshoot of Europe. Is it the same? No, certainly not. But I would think culturally Canada is at least as similar to France or Britain as France or Britain are to Finland or Moldova. You have a point about the military threat of Russia. But then again, Canada and Russia are the countries with the two largest arctic coastlines.

We're in the 21st century, and on a planet that is rapidly warming. You need to start thinking of this perspective:

You need to imagine a future where this ocean is populated and as active as all the other planet's coastlines. Canada is closer to Russia than Spain or Portugal are. They don't face a land threat from Russia, but they do face a maritime threat. Now, admittedly, the worst Canada really has to fear from Russia is perhaps Russia trying to seize Arctic resources or shipping routes from Canada. They don't face the existential threat of direct invasion and subjugation like Finland. But then again, it's not like Iceland is facing a serious threat of Russian invasion either.

Personally, I can see little reason for allowing Iceland but not allowing Canada. Australia and New Zealand would be similarly easy to integrate from a cultural and institutional perspective, but there distance is a bigger factor. Canada is closer to Russia than some existing EU countries. That isn't the case for Australia. Canada might risk loosing access to Arctic resources in a war with Russia, but there's nothing comparable for Australia or NZ.