Perhaps. After all, the human brain is a complex thing. However, even this piece hints that the guy might have had some kind of personality or affective disorder (i.e. his uncontrollable anger). That seems to fit the pattern of male behavior that involves gang membership (be it a fraternity, sports club, "secret society" or a street gang) and violence as the means of dealing with anxiety and anger. There is a similarity between this guy and, say, the "trench coat mafia" guys from the Columbine High - both felt uneasy and increasingly aggravated about the external world, and resorted to a "secret society" membership and eventually indiscriminate violence to resolve that anguish.
I think there is an affective defect in some (many?) men which makes them unable to deal with the outside world and their emotions about it (women seem much less susceptible). This defect is the underlying cause of the fear and anxiety which they seek to resolve through membership in rigidly defined ("secret" i.e. clearly separated from the rest of the world) and structured (hierarchical) social arrangements, such as fraternities, sports fan clubs, secret lodges, street gangs or even the military. That rigidity gives them a sense of security and channels their anger and aggression in one direction or another. In some cases (e.g. sports) that channeling produces relatively little social harm, in other cases (fraternities) the destructive potential is much greater, and in still other (gangs, terrorist organizations) - it is enormous.
One civilized way of dealing with these emotionally defective males is the compulsory military service - which gives them what they seek (a clearly defined social role and a sense of certitude) while keeping they aggressive impulses on a short leash. That is, until fascists gain control of the government and decide to unleash that aggressive potential - but that is another story. I think that the fact the European countries still have conscript armies (with the possibility to avoid draft by voluntary service arrangements) - which btw, have not been engaged in any major conflict during the past fifty or so years) - may the factor contributing to the generally less violent nature of these societies (e.g. vis a vis the US).
Wojtek