If they see it they ask you to leave, if you don't it is trespass. If you should use it legally in the resteraunt again you violate property rights, you were notified it is illegal to carry a gun on "their" property.

I'll choose to spend my dollars at another business. I'm a sales person and spend thousands of dollars a year entertaining customers, none of my company dollars or my personal dollars will be spent in these business establishments.