All right, disregarding the fact that, if you were forced to serve anyone, regardless of who they were, then you wouldn't be allowed to bar a known shoplifter from your premises, or that sleazy bloke who constantly makes off-colour comments to female staff or racist ones to Black staff or customers, let's try again.

Consider your own most deeply-held principles and beliefs. Now imagine that someone, in the way of legitimate business, asks you to do something that violates one of those principles. Would you violate your principles for the sake of profit or feel justified in declining? If the latter, how would you feel if the prospective customer then sued you for doing so?

You will undoubtedly wish to argue that your principles are in some way objectively 'better'. Bad news, they aren't. Objectively no principle or belief is better than another. Only actions can be objectively good or bad and the only measure of that can be the actual harm done by said action. In the two cases under consideration the harm done was minimal. No physical injury was sustained and nobody was deprived of anything needful. The need to look for another baker/restaurant qualifies as a minor annoyance at best.