Then claim freedom of speech, something that is specifically protected. Better yet, freedom of religion. Artistic expression is a lot iffier and something the courts probably won't have a problem ruling against. After all, are people able to walk around buck naked or paint graffiti on my house in the name of "artistic expression"?
I actually recall just such an event. Some clown in New York had a couple having sex on a sidewalk, a reporter asked him what made that art and he replied because I am an artist and I say it is art.
I can't recall for sure if he had a screen but I think he might have so it wasn't exactly in open view.
I guess you don't live in NYC.
Her lawyers likely feel SCOTUS, ie Kennedy, will be reluctant to back free exercise in this case. Framing it as a speech issue, being compelled to use your artistic talent for a purpise you do not support, has a better chance. The state compelling speech is likely to be more alarming if SCOTUS were to support it.