"He strong... very strong" is that correct translation? He sounds kinda like one of those retarded pawns. As Naruto said, he could really be some Orochimaru's half-successful experiment.
I say the guy is an experiment because he talks like a machine , one word , a blank , one word , a blank ...
I say Kabuto , because Kabuto should be respectfull regarding Itachi's behaviour , considering that Itachi let Kabuto find the real path to choose , although he could have killed him.