Ironically, he's teaching in Toronto. It's known that it's really easy to qualify for Canadian immigration once one has sufficient means. Good chances the people in his class benefited from corruption in their countries.
> I’m angry because Nazis are on the march once again
My advice is: don't tell that to a WW2 vet...
> I do wonder if things like volunteer teachers don't depress other teachers' wages. Therefore indirectly the quality of teaching.
It's much worse. The class he's happily teaching for free would have been handled by a grad student (doing real research and publishing) and would have helped him cover tuition.