Permit holders may have loaded firearms in personal vehicles in public and private parking lots, and as of of July 1, anyone not prohibited from owning firearms may do same.
Only exception is if it's contrary to federal law. Airports are not federal facilities, so not sure any way could be banned in that manner.
Also, of course, it is perfectly legal to bring unloaded firearm into the airport to declare in checked baggage. Matter of fact, if airport is not posted no carry under 39-17-1359, it's legal to carry your loaded heater into airport, short of secure area.
My guess is it was some sort of explosive search exercise, either drill or because of some perceived threat, but who really knows with any of the 3 letter agencies anymore.