Dont' Neo Nazi's and Members of the KKK have rights too? It seems like when it comes to the topic of Gay rights, people aren’t allowed any options when it comes to their own sensibilities on the subject.
The thing with neo-nazis and KKK members is that they *do* discriminate and their events promote racial segregation, hate speech, etc. Refusing to serve them, when their viewpoints are in opposition to the civil liberties of the general public, would probably be legally permissible. If a group wants to promote their hatred, they can find someone who shares that viewpoint to do the stationery, catering, etc. I don't see a gay couple who want to spend the rest of their lives together in a committed relationship as a violation of anyone else's civil liberties. They aren't telling the JW stationery lady that she can't go Door-to-Door™ or attend Meetings™ at the Kingdom Hall™ or gather with other JWs at a Circuit Assembly™ or District Convention™. They just want to have a celebration of their relationship with their friends and loved ones - it is none of this JW lady's business to interfere with that.