As to the story, everybody knows you can't bring knives on board. If every time someone is CAUGHT doing so they get to argue that "it was a mistake", then the screening is meaningless. We have to be able to punish people objectively for objectively breaking the rules.
On the trip home, screeners with the Transportation Security Administration at Los Angeles International Airport found it deep in the outside pocket of a carry-on cooler.
The Cooler was a "carry-on", which means it was a SMALL cooler. How "deep" could the outside pocket be? 4 inches? 6 inches? Maybe a full 10 inches "deep"?
It would have taken her a minute to empty the entire contents of the cooler, and repack it. EVERY person should completely empty their carry-on luggage RIGHT before they leave for their flight, and re-pack it carefully, to ensure there's nothing hiding in the bags that would get you in trouble.
Yup. That's what I do, more or less. Learned my lesson years ago when security (pre-TSA) found a speedloader for my .357 in my bag. It was empty, and I had shipped the gun and ammo ahead of me... but the speedloader was down in a pocket I hadn't checked. It caused... some ruckus. :-)