@Mark: I'm not certain if I understand, but I'll go ahead and point out that you are right, our ability to say "No" is not absolute. However, I'll add that no one is asserting otherwise. From the majority Supreme Court opinion:

"The dissent labels the distinction between status and message 'amusing' and 'embarrassing.' But in doing so, the dissent ignores a fundamental feature of the Free Speech Clause. While it does not protect status-based discrimination unrelated to expression, generally it does protect a speaker’s right to control her own message—even when we may disapprove of the speaker’s motive or the message itself. The dissent’s derision is no answer to any of this."

So, it sounds to me like the Court is pretty clear in its majority opinion that our right to say 'No' is not absolute; or, as it states in its own legal terminology, the Free Speech Clause "does not protect status-based discrimination unrelated to expression," but, "it does protect a speaker’s right to control her own message."

The whole question, therefore, seems to come down to whether or not the website designer's creations are "expressive" or not. And the court determined that they are. As such, they are protected from coercion by the state. But that determination does not grant a free license to anyone to refuse any service on any grounds.