Yes, it's fine. The property owner should be free to choose who he allows on his property, period.
By the same token, those he offends can "vote with their wallets", and do business elsewhere, denying him the profits he would have made.
It's called "freedom of association".
And it would be legal to forbid "negroes" and "Messicans?"
Sounds like someone is condoning doing away with an amendment or two in the Bill of Rights, which is the same thing we accuse anti-gunners of.
Scary stuff.