imo turning good after you've committed mass homicide is a cop out

[SuperChief]

They didn't turn good, they saw the error in their ways. Both Obito and Nagato have referred to themselves as trash. They know what they did was wrong and saw the error in their ways in the end and tried to go out doing the right thing even if it didn't redeem them. They could've easily done nothing but because they did, Naruto can respect the person they really were all along. In a way he admires their strength and capacity to change because that's how he stayed on the righty path. It took strength not to turn evil and it took strength to return to the good.