I think you're right and I may be confusing the civil rights act or maybe the unpassed equal rights amendment with the 14th.

As far as this refusing service, I generally agree with you principle, but I think there are some scenarios that could make this...complicated. For example, you are in a small town, a man has a medical emergency, and there is only one doctor in town - a refusal to treat certain groups of people could be awfully problematic in terms of real world outcomes here, even if as I say, I agree with you purely on principle. I think society would have to be structured somewhat differently for this to work, i.e. people all lived in communities with their own identity group so this doesn't happen.