"I can point out where I have the right to keep and bear arms recognized by the Constitution. Where in the constitution is the right for property owners and employers to remove other constitutionally guaranteed rights? What other rights can they forbid?' The Constitution forbids government from restricting rights. A property owner can set virtually any rule he or she wants to grant access to their property. Go to work in your underwear and a pair of flip-flops and tell your boss you're just exercising your freedom of speech. Come back and tell me how that works out for you...
The Constitution, in part, recognizes mans natural rights which are not dependent on government and are not void because someone is on your property. You can ask someone to leave your property but you can't remove their rights. I could go into work with flip flops and underwear and I would probably be asked to leave and not come back unless I visited a psychiatrist, (unless I suddenly claimed to be gay, but I'm not sure they would buy that drastic of a change) regardless they could not hold me and force me to dress in the manner they chose simply because I am employed by them.
In the spirit of your challenge I suggest you put a sign on your place of business/property line that says "No Blacks, No Irish, and No Muslims allowed" and see what happens.