Should you be able to keep blacks out of your business? You never answered the question.
Yes. Definitely. Absolutely. Want me to go on?
Conversely blacks should be able to keep out whites.
Once you let government tell you how, why, where, when and how to run your business it's no longer your business.
Think about the transvestite in California who wanted a job as a waitress because it was "her" civil right. That's the logical conclusion to government involvement in business. The owner loses control of what he paid for and built up.