The article suggests this is rare and unheard of, but this is exactly what my Dad had. Right down to the tiny bit of brain left around the edge of his skull by the time they got around to inventing CAT scans and doing one on him. He died when I was a young adult, of an unrelated medical condition (lung embolism). The hydrocephaly affected his motor skills, and his mental state resembled senility — if you talked to him for an hour you might notice nothing out of the ordinary, except for his inability to walk far without falling down, but if you checked thoroughly you might find he was misremembering things, or didn’t really have an accurate grasp of what was going on, didn’t realize the extent of his own impairment, and that he made irrational, impulsive decisions like buying things advertised on infomercials that he couldn’t pay for.
Once he got an accurate diagnosis a shunt was put in; it relieved the symptoms somewhat but he never got anywhere near normal.
This guy sounds like he was just in a less advanced stage of the same thing; I hope they caught it early enough for the shunt to have a really salutary effect.