Well, This was confusing for me as well. Why didn't he do the deed then? Why did he need to heal them?
The only hypothesis I can give is that Sasuke needed their aid in battle, and when the war was ultimately over, he finally had the chance to kill them in peace and quite.
Ikr! They did nothing to help. Then again, if Gaara wasn't there, Naruto wouldn't be alive right nowThat was am thinking but the kages wasn't much help at all during the war