You don't think its reasonable that they would find this upsetting?
Listen. Whoever lived through the Holocaust is old. He was a small child during the Holocaust and saw things he'd rather not remember. It may have started with a few swastikas on his local synagogue. It may have continued by him no longer being able to attend school, or go to the same park. And then the jackboots came in the dead of night and took away his Daddy...
How do I know? These are my father's own memories. If my father were to see that again today, it would break his heart, too, to think even for a second that his grandchildren might have to go through what he and our family did.