Thank you all for your comments.
Just to clarify some of your doubts.
In no way I had the intention to imply that this behavior can only come from a Qatari. The nationality just became an issue as he was screaming his lungs out that he was a Qatari and the plane was qatari and therefore he was inside a qatari property so he had more rights than any other foreigner. And he went on that he would not allow the seat in front of him to be reclined because it was not comfortable for him and that the crew were serving his country and they should not dare to offend him. When the crew politely offered him to move to another seat with no one in front of him, he refused and instructed the crew to move the passenger who was sitting in front of him.
He kept shouting in a hysterical voice and kept punching and kicking the seat in front of him. All the other passengers were shocked and couldn't believe what he was doing (specially that he himself had his seat reclined). Most of the passengers were westerns on transit to other destinations and started to talk to him and things got a bit out of control. That is when the crew decided to communicate with the captain, and shortly they announced that security would be waiting for the aggressor at Doha airport.
Meanwhile they convinced the aggressor to move to another seat and he said he would only move if the victim (not me, Mr. Bleu) would move too. The crew convinced both to move and by then most of the passengers nearby were shocked and could not believe that somebody would claim national rights over an aircraft.
Once the flight landed, no security was waiting and the aggressor left freely the aircraft. Upon arriving at the airport terminal, he went straight to the passport control for GCC nationals section. He was greeted by a local official who chatted with him, laughs and hand shakes were exchanged before he cleared immigration formalities and then he went off for luggage collection. This was witnessed by myself and other passengers in transit. They were even more shocked with what they just witnessed than the scene inside the aircraft. They could not believe what they just saw. I told them, as a resident, I was not surprised at all, this is the Qatar way. When I arrived at the luggage collection, there he was (the aggressor), as if nothing ever happened.
As Ummjake said, the lack of any punishment, just continues to stimulate this behavior and does nothing for the evolution of civilized behavior of certain people here in Qatar, on the roads or on board of “their” aircrafts.
It is the behavior of people like this that give Qatar a bad name. With all respect for all the educated Qataris, this will go on until Qatar is a state governed by the rule of law, applied to all inhabitants equally.
I will update you here on the response from Qatar Airways.