It’s not a lie to say you are artistically not interested if you are not interested in that aspect of art.
Since that is not their reason for turning down the business then yes, saying you're doing it for artistic reasons would be a lie. And since their reason for turning it down is it violates their religious beliefs then I can understand why they would not want to resort to falsehoods. And the government should not encourage them to do so.
Avoiding confrontations with fascists just means that you postpone the eventual confrontation for a bit. It's still coming.