She isnt very dark and braids are not unsual. I think it was the top and I agree, we are not hearing the restaurants side.Everyone was allowed in the restaurant except her. There are no pics of what the group looked like, though a restaurant like that should have security cameras everywhere including the entrace. The security video should have that on display.
Who knows, maybe some of her other friends are as dark as the woman in the pic and since they were allowed in, the couple decided it was the braids when her blouse is obviously not allowed in such establishment. It could be an attitude problem too, as you said.
There is more to the story not being sid by them.