I don't know if there is any case law... we didn't have this issue with people carrying long guns into restaurants until recently.
Funny you screaming at me, but the Open Carry Texas posting says that they aren't real sure on it and have asked for the AG to review it.
So, you don't have a case. Were you aware there was no basis for your position, or were you hoping none of the Jim Bob/ Joe Bob hicks would notice?