Situations kept changing....and ofcourse he was a kid...what do you expect? Although ur claim seems to be true at a certain level, u cant blame him completely.
So you think people shouldn't be allowed to change their minds? He kept finding more and more about the events behind the massacre and he changes his goal for that reason, I don't see what's so difficult to understand about that.
Everyone changes their mind like this too including you. I seriously doubt you think exactly the same as if you were three. If so, that means you didn't grow up/learn anything at all