I interpreted "extremely normal in all respects" as meaning he's someone you wouldn't mind working with. You see, a lot of theoretical physicists are brilliant but have very difficult personalities.
It's not particularly enlightening or anything, just lending his name to the movement.
To me, the quote from Wigner clears up the author's meaning. Wigner stated, "He is a second Dirac, only this time human." Dirac was brilliant, but he may have had a high functioning form of autism which left him socially crippled. He was painfully shy, he didn't have many friends, and social interactions with him were extremely awkward.