Word will get out among the local pervert community about how horrible the bakery is...problem solved.
I'd not even go that far.
I'd bake the cake. And deliver it. With a big smile on my face, and a note....
"Here's the wedding cake that you forced me to bake. While there were plenty of other bakers who would have appreciated the business, you chose to force me to perform this service for you, for no other reason than, "You Could".
"While you enjoy it, think about the fact that, thanks to you, I've incurred substantial legal bills and had both my business and very livelihood put in jeopardy. Both myself, and my family have been subjected to numerous verbal and physical threats from people just like you, for no reason other than you felt the need to score a few political points at my personal expense.
"So.........Bon Appetit!!"
Man, I'd not go within 100 feet of a cake like that.
Word will get out among the local pervert community about how horrible the bakery is...problem solved.
Anything that isn't an outright refusal is a victory for "big Anus."