He thinks that just because a certain person he used to know is trash because the person turned evil
The same thing can happen with Obito..Because he turned evil he will have no choice but too kill"Naruto, Now do you understand? This isn't the sasuke you knew!"
But in all honesty, Hasn't he learned his lesson with the "death" of obito? I thought by then he wouldn't go by all the shinobi rules.
This is the only thing that spoils his potential...Other then that I really have no problem with him