I can certainly understand where Six Flags is coming from though. It's a park with rides that put amazing force on the human body. Imagine if somebody is riding a ride and their pistol comes out of the holster. The pistol lands who knows where and somebody picks it up. Sounds like a pretty reasonable thing from their part.
Also, I looked for it and remember it but isn't there something in the law about not carrying in places that charge admission? Is this GA or another state?