So this is the evil Shanks I've heard about?
Whoever says that shit is wrong. For the record, I've never parroted that idea. All I've said is that he's not who we think he is.
And he's not, specifically because of his connections to the Gorosei/Sengoku and his very clear cut objective to hurt one of Luffy's fleet members and go after One Piece. He also clearly manipulated Luffy and
Yes, he can care about Luffy and Momo. Yes he can save countries and live in peace. Yes he can stop wars in the name of peace. That's entirely the point. He is trying to achieve "something".
It could be good. It could be bad. It could he manipulative. It could be completely fucking grey. We just don't know.