You don’t have to bake their cake, it’s a contract not slavery. People can pick and choose if they want to work on a project or not.
At the point when government steps in to use force, this nonsense becomes slavery and an act of evil, rather than merely perversion. When you can no longer pick and choose if you want to work on a project or not, the entity using force to compel action is no longer the friend of any decent person, and the situation has crossed that terrible line into slavery.