Fine. In a free country, a person or a business SHOULD be allowed to serve or not serve anyone. It's an issue of freedom and liberty.
The other side of that coin is that you also have to suffer the consequences of your actions. Unless you live in Podunk Junction, Mississippi, bigotry will be met by protests and boycotts. That too is freedom.
At what point does a person's right to "freedom and liberty" encroach on another's right to equality and fair treatment? If they are a minority, and culturally despised - who will stand up for their rights in the thousands of "Podunk Junctions" around the country? Who will rent them a home, serve them dinner, or allow them to shop in a mall?