One of them apparently was loaded, according to the story. Of course that might just mean there was ammo in a magazine, separate from the gun. Some idiots in govt consider that a "loaded gun". Having a loaded magazine is not necessarily a crime for airline firearms transport. If i remember right, it's more of a policy with specific airlines. Some consider the magazine a proper ammunition case, others require ammo to be in the original factory box. If the rifle was truly loaded, his bad.
I'm curious about the "defaced" part. Did the paint really completely cover up the serial numbers, or did it just make them a little harder to read? In either case, they are still present.
I agree he should be cited for what he did to the rifles. Yuck.