Just listened to the podcast and this thought came to me.
The way I see it if you have a store/hotel/restaurant open to the public you are not private property any longer.
My home, factory or a club based on a membership can be private and set any rules they like, but once you open your doors to the public at large, you no longer have that ability. (And the truth is even those are highly restricted. Try and have a factory that will not hire based on age, race or gender.)
When an area open to the public, like McDonalds, can post and enforce a no jews, no women or no blacks policy then they should be able to post a no guns sign.
It's the same Constitution and BoR that prevents discrimination based on age, race, religion and sex, why then can I be discriminated against because I carry a gun?
Has this challenge to no carry laws ever been tried? Just a thought. Am I crazy?