>>If 2 men ask for a pink cake with chocolate frosting and a straight couple ask for a pink cake with chocolate frosting, there's no inherent difference in the product, and thus in the production.
The only difference is who the consumer is. Also, the hollow difference between "I created this just for you" vs. "I created this, and you will be using it" of your pre-baked vs bespoke cake example seems extremely weak to me. Legally, this doesn't matter, but hey legally at one point black people couldn't vote because "reasons".
The point I'm getting at: Why was OP comfortable with half measures? Why is "black" a protected class, even against "deeply held religious beliefs" but "gay" isn't? Why is "use a product you created just for me" different from "use a product you created"? This difference feel arbitrary to me, and grounded more in homophobia than any sort of sound logic.
Put bluntly: If you think gay people shouldn't be allowed to request cakes, I don't see how you can logically hold the belief that black people should be allowed to request cakes.