Shoprite refused to decorate a cake of a 3-y-o boy three days ago. To his mother, "That's sad." Of course, she and the father named the 'lil tyke Adolph Hitler Campbell. Boy, I wish I was making this stuff up.
From a purely academic point of view, can you refuse to put a name on a cake? Sure, you could refuse to put a 'bad word' on a cake citing decency, but here the refusal is based on an objection to the beliefs associated with the name. It is a service offered to the public, so Shoprite can't discriminate ... of course, whites - including white supremacists - aren't a protected class. Or perhaps they post somewhere that they reserve the right to refuse service to anyone. Maybe that's the easy out.