I'd be worrying about infection getting into the brain from a wound like that. Fair enough to just pull it out, but how did they clean the wound? Although I suppose the nail would have been pretty much sterile (not having been handled at all, or been kicking around in a bloke's tool box). Still, that's a deep, narrow wound and I would hope they made sure that bacteria from the scalp weren't driven deep into his brain.
Marg