What is gay couple is making a scene in a private space and demanding a cake? And the bakery happens to be by the church and having gays hand-in-hand would severely hurt their business? What if instead of gays it's cyclists in undersized lycra? I'd rather not have either of them kicked out.

I'm pretty sure abuse of return policy is covered by some kind of law. On the other hand, blacklisting customers who just use advertised return policy to it's full extent is not moral either. False advertisement is breaking of the law too.