GuyRelford
Master
If I am reading 35-47-11 correctly, it doesn't say anything about buildings vs. other properties (eg: parking lots). It just says "a political subdivision may not regulate".
On down it provide an exemption for BUILDINGS with court rooms or metal detectors (with restrictions). No mention of exceptions for other property.
So, I assume they have the ban in place illegally.
I think you're exactly right.