But if the idea is to create a unified and peaceful humanity, destroying humanity to achieve that seems like an oxymoron to me...because he's not really teaching humanity to get along and appreciate one another, but controlling it so that it gets along. And his alien threat might unify humanity, but it is based on fear, a fear that can grow and project in many ways. I do not think I can consider this as peaceful.
And in doing this, he's effectively using fear in order to control them, reducing their freedoms by necessitating their actions. He's limited the choices for humanity to make its own decisions and mistakes and then not giving humanity the choice to learn from those mistakes either. He is then not teaching humanity how to learn from its own mistakes or to learn from its mistakes, but limiting freedoms so that they don't make the mistakes altogether. He is limiting humanity's growth, because growth means making mistakes and not having peace at times.
I might be biased, but I can't see anything truly...moral...about his approach, though his character may feel motivated by the idea. I guess if the idea is that limiting choice through control is necessary for peace, maybe someone could make a good argument in favor of his approach, but I feel it is an idea that is against an appreciation for life.