Hunka was part of a division of Ukrainian volunteers under Nazi command.

This is minimizing it. He was part of the 14th Waffen Grenadier Division of the SS. (From Wikipedia:) The SS was the military wing of the Nazi party. The man swore an oath to Hitler.

I understand that a young man that:

-Grew up in a region recovering from the Russian Civil War
-Grew up during the mass murder and starvation of the soviet purge of the kulaks
-Was subjected to nationalistic propaganda  (Nazi and other)

might have great animosity towards the Soviets, and be inclined to join any force opposing them. I'm not asserting that Hunka was a bad person and should have known better, but he may have been. I'm not saying Canada was wrong to admit him as a displaced person, but we might have been. To minimize the Nazi ties of the Waffen SS is not responsible.

His division might have:

Wikipedia references a publication that claims the Soviets managed to capture several hundred of the SS division in question, a few weeks after the massacre and concluded they had participated in the massacre. The captured SS soldiers were executed. Maybe none of the guilty survived.

Parliamentary guests should be vetted. I actually think a letter from Hunka decrying propaganda, dictatorship and imperialism and celebrating a democratic and pluralistic Ukraine would have been a great thing to applaud in Parliament.

We should mock anyone saying this procedural failure shows Ukraine has significant Nazi sympathies. Or that Canada is soft on Nazis. This was a bureaucratic oversight that had embarrassing fallout. I'm angry that it happened, but let's have a sense of scale.