zahavasdad
No, that is not the issue. That is a hypothetical case and there is definitely an argument to be made from a frum perspective that one should not bake such a cake.
The issue is whether you feel that the government has the right to compel you to serve someone. It doesn’t matter if either you or the government can prove that your particular religion allows or disallows something. That’s not the business of the government. My answer is that no, the government should not be able to compel you to do something simply because it conforms to their definition of morality. That is the essence of the freedom to practice religion.
And nobody has the right to be served. The only time anyone had the right to be served was during slavery. And anyone who is against the Indiana RFRA would tell you that slavery was wrong (as would I).