It is no more racist to put on a native american headress, than it is to be non asian and wear a kimono. People need to have a seat.
He wasn't wearing it in mockery. Now if he put it on, and painted his whole body red, than that's a whole other issue. But just to appreciate other cultures clothing and wear it? So should black people not put on greek clothes? Should white people not wear a kimono? Should an asian be called racist because he wan't to dress up like an aztec warrior?
People were making that thread to cause mess. They know good and well there was no racist intent.