I actually generally agree with this.
While I normally side with the liberals on some issues, including gay rights, when it comes to businesses, this is one place where liberals and I part ways.
I am a tax preparer, and own my own business. If I wanted to say that I refuse to do taxes for, say, gay couples, or Republicans, or Democrats, or white people, or whatever demographic, I should have the right to make that decision. It would be a STUPID decision to make. Why would I want to deny business? I want to serve as many people as possible. I don't care what your story is. Unless you're asking me to commit tax fraud, I want your business.