TSA: Gun OK, Knife Not OK

Techdirt posted an article about the TSA: We've Trained The TSA To Search For Liquid Instead Of Bombs. It's just another security theater example. But somebody posted a comment that might be the best example of TSA absurdity yet:

As a federal agent, I'm authorized to fly armed, so on one trip, I was clearing through security, the airport cop had checked my ID and paperwork and approved me to pass through the checkpoint, but the TSA guy stopped me and said he needed to inspect my carry-on.
I asked why, seeing as how I'd already identified myself as carrying a loaded handgun, what could possibly be in my carry on that would make me a threat, and out of hundreds of flights, I've never had to be inspected before.
He claimed it was just procedure. (If that's true, it's a procedure that has never been followed before, to my knowledge.) But not wanting to create a hassle for myself, I said fine and let him look through it.
Well, he came up with my Leatherman knife (basically a fancy Swiss Army knife) and said that I couldn't bring it on the plane because knives are prohibited items.
I looked at him like he was insane and said, "Let me get this straight, you're letting me carry a loaded handgun onto the plane, but not a pocket knife? In what conceivable world does that make sense?"
He responded that per FAA rules, I was authorized as a federal agent to carry the gun on board but the rules don't mention knives except as a general prohibition for everyone.
Not wanting to lose a $30 knife, I asked to see his supervisor, figuring this was some low-level zombie unable to exercise basic common sense. But no, the supervisor said the same thing!