As much as I don't like the choice the business made, I don't feel they should be forced to do business with someone they don't want to. A business can deny me service for any reason. At which point, I'd suggest they respectfully go play in a fire while I take my business elsewhere. All while suggesting to friends / family / random strangers on the street that the original business is crap, and not to contribute to them.
Taking away any person's free choice is a crap shoot. If a customer came in being a complete tool, and I owned the business, I should be able to say "No. GTFO!". This could be for any other reason, because it's *my* business. If I choose to suffer the consequences of not having their business, that's my choice.
We're not talking governmental services. Obviously, if the police, fire, EMS, or whatever other necessity out there said no, there'd be issues. But we're talking a business that provides baked goods.
EDITTED TO ADD: As a side note, I've been denied service in the past because of my personal choice to carry a firearm for self defense reasons. That's the business's choice. I could pretend that I'm entitled to be served, but I'm not. Freedom of choice is a valuable thing. Other businesses have now received my business, along with my family's. Does it make me happy that my values were undermined by a business? Not at all. But if they don't want to serve me, I'll go elsewhere. Big deal.