They have religious freedom, but at the same time the laws of the area say "You cannot discriminate or refuse service to X Y Z groups". If they want freedom to discriminate, then it is only fair that I get to discriminate against any religion (or lack therof) in return.
At the same time, they're a private business. I would bet money the couple went there with the
sole intention
of being offended.
"Can you connect to Judgment if you have a yarr harr copy?"
- Googledotcom