They have so much invested in all the TSA bs they can't admit any possibility of failure.
I don't know, with all the "layers of defense" BS we were fed during training, I highly doubt this. The biggest problem with the TSA (and I don't mean just the guys in blue shirts at the airport) is that it is way too political, and decisions are made for all the wrong reasons. In addition, everything implemented is always reactionary. Remember, taking your shoes off didn't happen before Richard Reid. Full pat downs in place of hand wanding didn't happen prior to the Underwear Bomber. The liquid BS didn't happen until after they found some terrorists were planning on using those in an attack (even though they knew liquid explosives could be used...look up the Bojinka plot). I suppose this is the way Government works.
But hey, an FFDO hasn't had to fight off a bad guy, so it must be unneeded. But Air Marshalls haven't had to fight a bad guy either, so let's cancel that program too. Working for TSA for so long was frustrating. One of the things we used to do in our downtime was to talk about how we would change airport security if we were in charge. We'd come up with a plan that would require half the number of screeners in the workforce, would be FAR less invasive to passengers, AND speed up screening. And it was all common sense stuff. Unfortunately, as a Government employee, common sense was prohibited. You were expected to be a robot with flesh.