It should be an open-and-shut case: If you're a business owner, and you're foolhardy enough to turn away customers, that's your prerogative.
Billy Hallowell could be giving positive publicity to the business owner cashing in on Jack Phillips' excessive interest in his customers' private affairs, but instead he's chosen to write the story as follows:
Should any court in the United States even hear this complaint? If Phillips wants to tell some other customer, "I'm not baking a cake for your daughter's wedding because she can do better than to marry that young man," or maybe, "I'm not baking a cake for you, period, because you borrowed something from me and didn't bring it back," that's his privilege. And someone else's gain.