Good find on those pics. I have some issues with almost all of them.
The "we're a culture" theme is off the mark with the arab thing. I would assume the arab fellow would deny that suicide bombing is a part of his culture. The costume IS a part of his culture, but if that were ALL the guy was wearing (w/o the bomb) would the arab kid still find it offensive? If not, there is yet another hole in the poster's theme.
OTOH, the Geisha is a part of Japanese (and to a lesser extent Chinese) culture. However, it is a historical part. The costume is a historical costume. Like someone dressing up as George Washington or a wild west cowboy. I truly wonder if the Scottish are offended by someone dressed up as a bagpiper or William Wallace? Somehow, I doubt it.
The one chick in blackface makeup...now that could be offensive. It depends entirely on context. Is he dressed as an R&B star or rapper? Or is this merely a caricature?
And the bear thing. I was laughing so hard, somoene came to my office to see if I was ok.