I'm not sure this is as bad as y'all are making it out.
He's not charged as a terrorist. Virginia law prohibits carrying a gun into the airport property. It's a misdemeanor, and won't even keep him from renewing his gun permit. He should have known where his weapon was, and where he was, this knowledge is required to obtain the permit to carry in the first place (I know because I'm a Virginia permitee as well). "Forgetting" and "Mistakes" are things we should have low tolerance for (not zero tolerance, mind you) when it comes to weapons.
Now, if they'd charged him with a federal crime (for taking the gun into the sterile area), that would have been overkill, given that he came back and tried to correct his mistake. In fact, I'm pretty impressed that the TSA used their discretion and turned it over to the locals, who also handled it within their limits of discretion. Cops aren't allowed to say "go on, have a nice day" with this sort of violation.
I would expect the Virginia court system will either dismiss the case, or plead it to a lesser offense, given that there didn't seem to be any intent to commit a crime.