Colonel Miles Quaritch: Insanity's Edge?

[Banefull]

Quaritch seemed like a person who was dutiful but misguided. He did his job well. In any normal movie, he could have been the hero but here he was the antagonist.

In the original release, I had the impression that he kept his sanity throughout the film, determined to carry out his mission. Once the Dragon gunship crashed, he went out alone on what was perhaps a suicidal mission. Was it highly irrational? Yes. Was it insane? quite hard to tell.

After watching Avatar CE, the Quaritch-Selfridge deleted scene before the final battle gave me the impression that Quaritch had gone over the edge when he took over the base. The look on his face was that of a person consumed with fury. In the extended dialogue between Parker and Quaritch before Hometree was hit, Quaritch seemed a lot more assertive of his intentions and far more desperate for any kind of fighting.

So did Colonel Miles Quaritch ever reach the point of insanity? If so when did he become insane? Was it when he took over, when he set off alone in an amp suit, or at some other point in the movie? Was he insane from the beginning?