Not one person who was responsible for that genocide is now alive.

That's very likely also true of the Jewish and Gypsy Holocaust, and soon will be anyway. But if there was a government in Germany today that was dedicated to denying that the Holocaust had taken place, and a legal system that jailed people for insisting that it did, I think it would be relevant to challenge that in every available forum, including national parliaments.

One thing that might help Turkey come to term with this would be for the genocide of Native Americans to receive some analogous formal recognition.