Not only that, but forcing him to provide goods/services violates the 13th Amendment -- Sec 1 - Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
Courts don't apply the 13th to restaurants that deny blacks. They uphold the anti-discrimnatory laws. If you choose to be in the restaurant business, you must serve blacks and that's not considered involuntary servitude.
The question is whether or not the court can see that this is fundamentally not a racial discrimination, but rather a participation in a ceremony that violates the defendant's religious beliefs.