That one in particular? No clue. I'm not sure what google scholar's criteria are.

I know things on utoronto.ca turn up sometimes for a example that does (UofTs non-edu domain name, which is used for most things. Though toronto.edu is also owned by the university and used for some things).

TLD alone would certainly not be enough of a filter. Scholar has to account for scientific publishers that use TLDs like .com and .org and other non-school websites that use ccTLDs.

But Scholar proves it is possible to usefully filter for peer-reviewed papers.

Filtering is never "perfect". The question is whether it is good enough to be useful.