I still wouldn't kill my family just to protect my brother. There's always another solution.

I guess what he found out from being a spy was just to convincing. Also, I still don't buy that he killed his whole clan, we never see him do that. At the end, it's him that uses the sharingan to implant those images into Sasuke's head.

And...it's hard to believe their mother was in on the rebellion. I find it strange that she says to Sasuke: "Your father talks only about you."