considering Canada is full (literally, no housing),

That has to be the STUPIDEST logic I have ever read. Like seriously, how ignorant do you have to be to conflate the housing crisis with Canada being "full".

Never mind that we have literally millions of acres of habitable yet undeveloped land, many currently existing dwellings aren't even occupied. There's a significant portion of the housing market that people are squatting on as the prices raise. This restriction of the supply is literally what is driving up demand.

To see this artificial limitation of housing and draw the conclusion of "birth tourism bad because we are full" is literal nonsense.

There's plenty of good reasons to be against birth tourism, so pick one of those.