how she even got the gun through security.
You can quite legally transport a firearm in your checked baggage, because it's not accessible to you during the flight.
But yes, the TSA is a joke, and red teams have roughly a 90% success rate at getting firearms and simulated bombs through "secure" checkpoints. It's security theater; it catches people that aren't really trying very hard--or truly forgot that they weren't supposed to carry a firearm in their carry-on bag--and it makes the majority of people think that flying is completely safe. Not very long after 11 September, I was flying to New York City with a friend that accidentally had a rather large switchblade in her carry-on, at a time when switchblades were illegal throughout the US. Not only did she carry it to NYC, she was able to get it back to Chicago, all without the TSA noticing.