Even if it was in 2006 rather than 1942, would it be any less offensive to victims of the Holocaust, WWII vets, or their descendants? I don't think we can use distance as an excuse. If this kid shouldn't dress up as a terrorist, then no one should dress up as Stalin, Hitler, KKK, blackface, Steve Irwin, Cory Lidle, Tylenol pills or anything else.
"It's obviously done for shock value, so don't be surprised if people are thoroughly shocked."
True.
But I'm not suggesting that people can't dress as Hitler or Stalin or KKK, nor that some wouldn't find it offensive.
I'm offering an explaination why more people in 2006 would be shocked at seeing a terrorist bomber costume than a Hitler one. And that a Hitler costume today would generate less overall shock than it would in 1942.
It's human nature that time has an impact on people's emotional reaction. I'm Jewish and a big branch of my family tree was severed during the Holocaust. I'm quite sure many of my older relatives would react quite different to seeing a Hitler-costumed youth today than they would have in 1945 after seeing images of the Holocaust for the first time.