Must I also allow my employees to exercise their other natural rights? Must I allow their freedom of speech/expression? If they have a klan sticker on their vehicle must I allow them to park it on my property? I would say no, I don't.
I may not fire an employee that is a member of a protected class for being a member of that protected class. I also may not eject them from my store, for example, for being a member of a protected class.
Now I don't own a business anymore, so it doesn't really impact me. Also, in VA, our attorney general just put out an opinion that a property owner may say employees cannot keep guns in their vehicle on the property if they wish. I agree with that decision. As I said, I have no problem with people keeping gun in their vehicles on my property. And, it should not be an issue unless the person that has the gun in their vehicle makes in an issue.