I dunno but wasnt his character all about protecting Sasuke in the wrongest way possible... he had to do what he had to do even if it meant being a traitor to the entire village... kinda like Boss from MGS
You don't get to cry, Itachi. What are you doing here anyway? You're the "Aloof Brother" to a horrible degree!
You sure you ran through the series the right way? Or are you leaving anything? And here I thought it was obvious why he did what he did the moment they talk about how he killed the whole clan but his little brother. I had no proof at the time but Kishimoto freaking proved it.