Shes been right about everything. Even the time Rick banished her (and we know what happens to pretty much anyone who disagrees with Rick no matter the hypocrisy) she was right and it kept her alive. Someones going to die now because of Morgans actions. Neither of the Morgans (first season or this one) are in moral alignment with what this world demands from a person. He's going to die for it.
Carol makes the hard decisions that people generally wish they didn't have to make, and she acts for the good of all. Morgan, with his stance, is actually refusing to make a choice on anything because it's too tough to do. The only choice he is actually making is to never make a choice. He has already allowed people to escape, who will return to kill. And because of him they have guns now. He has latched onto this "never kill" thing as a crutch to enable himself to forgive himself for his past killings, just as his predecessor did for the same reasons.
Carol shouldn't have attacked Morgan, but they have to kill the wolf.
While Morgan's philosophy is admirable and sometimes effective, it stands to reason that some people are just too far gone as can be seen by the Wolf that has potentially killed the nurse woman, or by the governor. But some people are still not too far gone when they seem to be, like Morgan himself. However, I guess my real answer is that neither are correct, Carol is probably too murderous, but Morgan is too pacifist.
Carol was willing to potentially kill Morgan too.
I'm inclined to believe that trying to be better is what's going to help people move on from the whole zombie apocalypse. People like Morgan try to inspire people to be better and to help everyone else be better. I love Rick and Carol and all of them but they're gunna be f@cked up in the head when this is all over.
I love the walking dead but if you try to take Daryl away from me I will push you off the grand canon with a parachute of course because im not mean but i will still not like you. I might even have to put a Lego under your foot.