So Kakashi imply that it's not ok for Naruto to kill his favorite student but it's ok for his favorite student to kill Naruto?
This is when i'm starting to really hate Kakashi , the first time i'm starting to dislike him is when he throw Naruto to Ebisu so that he can focus teaching Sasuke.
It shows how much of a hypocrite Kakashi.
And it's worse for Kakashi as the Chidori is classed, for SOME reason, as an assassination technique, as in its main purpose is to kill.
The Rasengan, however, is an incomplete technique that can at least be used in a way that DOESN'T kill, but merely disable as Jiraiya demonstrated against those ordinary mooks when he first showed it to Naruto when searching for Tsunade.