I'm very skeptical that it's an accurate account of what happened to him. It goes against everything we know about the effects of sleep loss/deprivation, and I'm extremely doubtful that a brain injury (especially the frontal lobe, which is not related to sleeping at all) would change that so significantly, either. I could believe the part about him not being able to sleep; there are some diseases that cause it too, but I don't believe he would have been able to live for another 40 years. Maybe he slept 2 hours a day? Maybe he experienced multiple microsleep episodes each day? As @Bluewolf said, it probably got exaggerated over time until it became an urban legend of sorts. If the story is true after all, then he indeed was a medical oddity. It's a pity that more data is not available; neuroscientists would have a field day...