I think at least in theory that yes, that they can cater to whomever they'd like to, with a few caveats.

I guess it depends on what you mean by "cater to." Because if it means outright refusing certain customers, I don't think that's right, under certain conditions. If the customer is being abusive or something like that, it's a different story.

But if it means that the business just doesn't "like" certain people or certain groups or subgroups of people, I don't think that's really ok.

Of course, the business has the right to do this under the law in the U.S., it's just that I think it's morally wrong. There's a difference between the law and morality. The law is much more permissive.