This is a bit off topic, but the reason the TSA exists was out of the need to address the liability issue for airlines, not to make anyone safer. It would have been easy enough to just pass a law defining what level of security was needed (there are lots of very secure, private prisons, etc.) and then forcing the private firms to pass frequent breach attempts, etc. The problem with this is that it would result in far more secure (and time consuming) security screening procedures.
Around the same time as the TSA was created, the government became the insurer of last resort for terrorism related claims over $1B. This was to avoid the inevitable consequence -- in order to be able to buy insurance against terrorism, airlines would have had to prove to the insurance company that they had reasonable security measures. This would mean a 15-20 minute screening for each passenger, etc. In other words, air travel as we know it would have ended.
The simple alternative? Let the government hire the workers and "outsource" the security duty from the private airports and airlines. Nobody is going to successfully sue the government for allowing an attack to occur, and now that it's outside the scope of responsibility of the airlines, the insurance companies are willing to insure against the remaining risk. The $1B ceiling was basically a handout to the insurance industry offered in exchange for bearing a lot of extra risk for free while the government got its act together post 9/11.
If airport screeners were private firms, then even if the insurance industry didn't force quality screening to occur, there would be public demand for it once reports of weapons being successfully brought through. In today's world, it's a crime to even try to bring a fake/harmless weapon through, so the public is essentially forbidden from independently auditing the screeners.
The blogger is playing it safe by using a metal case, but that only tests the metal/object detection capabilities and doesn't test for successful detection of any of the other potentially dangerous items (which are also likely to be easy to smuggle through).