You can fly directly between Europe and Tehran. I'm sure many fly to Tehran via Paris, Rome, etc, but those are the folks that can afford it. Apparently, this flight via Kiev was by far the cheapest option to get from Canada to Iran. I suspect that's why so many are college students, who are typically broke...
I get that. And the Ukrainian airline has great reviews and excellent safety (providing Iran isn’t shooting their planes down), and, being non-Western, has Flight Attendants who don’t have to walk through the aisles sideways (to say the least!).
But the proportion of Canadians are still very odd, at least to me...perhaps Blackface is loading up their country with more Iranians than I’d imagine.