You have to wonder about people who sue a photographer who doesn't want to do a same-sex ceremony. I mean, there are plenty of photographers out there, and why would you WANT an opponent of your same-sex wedding photographing it? Wouldn't it hurt the quality of their work?
If I were a gay couple, I would avoid photographers who had a Christian fish in their advertising, because they wouldn't be as good as a non-evangelical photographer.
If I were a photographer opposed to SSM, and someone asked me to do one, I would begin by unrecommending myself on just these grounds. But I think I would do it if they insisted.