The men in the UAE wear a kandura (which is the long robe), not just the royals. The scarf is a gutrah and the headband is an agal. It's traditional clothing that is mostly worn to protect them from the heat, sandstorms, etc. it doesn't have religious context (for men).
*its been awhile since I've been to the UAE so someone please correct me if I'm off-base.
Got it. I still think it's kinda odd to dress up in an ethnic groups traditional clothing for halloween? I'm not personally offended by it or anything though.