I have a tie-clip that is shaped like a (two dimensional) Colt revolver. It's a single piece of metal, with some nice detail in the surface, but still a small, less-than-one-inch long piece of metal with a clip on the back. A TSA agent took great interest in it, rotating it so he could "look down the muzzle", only to find, perhaps with great disappointment, that it was, indeed, a single, flat piece of metal. That didn't stop him from unclipping it, and rotating it around in his hands a few times before giving it back. I'm sure he was employee of the month.
I wish I could tell you they only hired people who showed great common sense, and Intelligence, but then, I'd be lying. Part of the problem is that TSA is one of those places that promotes the idiots. I know this, because my manager had the intelligence of a box of expended brass. The training on identifying guns, is actually pretty good. I can't go into detail, but a lot of time is spent teaching people to figure out what is a gun, and what isn't (including things like cane guns, zip guns, pen guns, etc). But...what you described is so obviously not a firearm. That just makes me glad to not be associated with that organization anymore...