No one that young would have the capacity to understand some of the contextual references required to write this piece. If you pay attention to the way LulzSec writes and words things, they aren't at all immature in their thinking or worldview. Ceasing to give a fuck about perceived trivialities is something that comes with age and seeing how the world really works. The confidence they have came with age as well. Neither is not a sign of youth whatsoever.
I'd guess mid-thirties for these guys, at least for whomever is putting out their twitter updates. This is someone who is basically immune to white-knighting and is a truly hard-core realist. It takes quite a while for someone reasonably intelligent to become that cynical, and then a while longer for them to act on it.
Anyway, I'm a fan of these guys. While I wouldn't do what they are doing myself, I certainly understand the mindset. I'm not quite sure I understand the arguments against what they're doing. The knee-jerk reactions of wanting to call them wrong frequently seem more immature to me than their recent campaigns. The real world is messy, and LulzSec's work is a valid reflection of that.
As far as the comparisons to sociopathic thinking, that's just ignorant. Sociopaths generally don't care about anyone but themselves and that's obviously not the case here. A sociopath would never release any of this data, and would simply use it for their own advantage, regardless of who was harmed.
LulzSec is gleaning entertainment here from the unwashed masses to be sure, but they aren't out there enslaving people with debt, indoctrinating them with religion, shooting them for protesting, putting them in cages for drug offenses, etc. All of which is completely legal, and in my opinion, far more sociopathic than releasing some bit personal data or playing a few practical jokes on people.
Do they really need a manifesto?