I've already experienced what will happen when he returns, Tenten. It is not merely a matter of a story that might be inaccurate or a path set up that he can turn away from. The suffering and deaths he causes with his betrayal have already happened. It cannot be changed any more than I could return and undo the harm I caused Hinata-sama in the Chuunin exams.

[There, see? Don't make him lecture you on the matter of what Sasuke's done, Tenten, only pain and suffering can come from that.]