Articles like this always carry the implication that people are generally well-mannered and understand the intricacies of manners, but it's the technology which lets them down. This is seldom the case, and in those marginal cases, the behaviour can be chalked up to an accident. The fact remains. Most people do not use proper manners these days, and the people who are not couth by nature are not couth when sites like facebook are involved.
this is reminiscent of the "television will ruin your eyeballs" scaremongering in the 50s. I hate that studies like this (limited, sociological in nature, poorly constructed and concluded) are picked up by the media and taken to the extreme conclusion.
just because one of the savants didn't manifest his savant behaviour until around about the same time he was hit in the head does NOT mean he holds the keys to solving why people become geniuses. this is also the reason the vaccines=autism debate gets all ballsed up. correlation does not imply causation. other savants have manifested their powers during similar timeframes, so it might be coincidental. (sidenote: who lets their child get hit like that and not seek medical attention, especially when the child suffers debilitating headaches for weeks after?)