The scary thing is that this is someone who has access to his private Facebook profile, aka one of his Facebook "friends". And he doesn't know who it is. There are traitors among his friends.
He has 1391 "friends" on Facebook. I think this is past the point you can claim to actually know all of them, or even recognise all of them in a crowd.
This is also past the point where you can fool yourself that anything restricted to "friends" on Facebook is actually private.