If the US became a worse option for Canada than Russia, none of this discussion would be relevant. For one thing, Putin wouldn't be running Russia. And the US would be a very different place as well. Either that or Canada would have to have been overrun by an incredibly anti-American streak that doesn't really seem natural in the country right now.

The Monroe doctrine is important, but it is currently nothing like what Mearsheimer claims Ukraine owes Russia, which is fealty. I can see many places where the cold-war order has gone away. Perhaps in 1983, someone like Evo Morales would not have been allowed to run Bolivia. Ortega came back to power and was not opposed by a new batch of Contras. Brazil suggested that it was friendly to Putin and was not sanctioned for it. I think the times when Latin America was dominated by a few US multinational corporations backed by the Marines have passed and now the dynamic is much more like the relationships of smaller independent countries around their larger neighbors. When we are describing what relationship Ukraine deserves with Russia in the modern world, it should be much more like the US-Mexico relationship or the US-Canada relationship than the pre-2014 Russia-Ukraine relationship.