You make a rather big assumption in your post that the same security screeners are still employed by TSA. When TSA took over, the contract screeners had to apply for screener position just like everyone else. Those who weren't US citizens were automatically disqualified. I don't know if the contracted screeners who worked at the 9/11 airports were hired by TSA or not. I suspect that you don't know the answer to that question neither. What I do know is that the re-hire rate for contracted screeners was somewhere near 10%. That means that a great majority of the contract screeners either didn't apply for TSA positions or they failed to qualify. There's also another factor: contracted screeners were the very last to apply per federal mandate, and many of the positions were already filled. Still, the fact is that a majority of the contract screeners were NOT rehired as TSA screeners.

As for procedures, just pay attention to what you're alleging. Just to illustrate how illogical your statement is, let's just say for example that a paper clip somehow was used as an instrument of terror. Should someone in TSA lose his or her head over the fact that paper clips weren't on the prohibited items list? I used an overexaggerated example to make this point: prior to 9/11, the focus was solely on obvious threat items such as bombs, grenades, improvised explosive devices, firearms and knives with blades that exceeded a certain length. Our cultural mindset was, in the event of a terrorist take-over onboard, to pacify the terrorists and cooperate with them in order to avoid any more harm, death or injury to any other passengers. Every terrorist incident up to that point supported this strategy as a sound way to survive a terrorist incident. The working assumption was that terrorists were only interested in landing the plane at a certain destination in order to make their demands known. No one imagined that terrorists would hijack a plane with the deliberate intent of dying on that plane with absolutely no intent of landing it someplace. 9/11 changed all of that.

I find it interesting that you suggest punishment when there is no indication of negligence, dereliction of duty or other criminal violation of procedure. The procedure itself was flawed.

If there's any area where perhaps negligence may be alleged, it would have to be with the intelligence and law enforcement agencies whose responsibilities it is to detect, prevent, counter and neutralize terrorist incidents. However, even then, there are many other factors that have to be considered first before pointing fingers at them. But what the hell, you just want to hang somebody, right?