After reading this, I place the blame with the passengers for escalating the situation.
A few lessons:
1. NEVER ask screeners to speed up their work. I have never heard of this having the desired effect in any country. At best, they will slow down, and at worst, what happened here.
2. NEVER tell the screeners that they are engaging in security theater or that they have failed to stop any threats. I guarantee you that they are not going to stop and agree with you.
3. Why would you ask "what law" prohibits taking pictures? Did you expect that he would be able to cite the statute and bill number?
This incident is unfortunate but not unexpected considering how the passengers behaved. My guess is that if it had happened in any major US airport, it would have been a lot worse.