If by AI "right" you mean exterminating the plague that is modern mankind. Well yeah, that is scary and probably correct.
Anna
Exactly the opposite - what you expressed, is a view heavily influenced by the cultural bubble you live in, and its current zeitgeist - none of which an AI would (necessarily) share with you.
If a powerful AI were tasked to achieve a certain goal, let's say the "advancement of mankind", surely things would happen that the majority of people today would deeply disapprove of - things like ...
- complete pre-determination of people's lives in order to support the greater goal (totalitarian).
- stopping the flow of resources to whatever parts of mankind the AI would consider "unproductive" (technocratic social Darwinism).
- prohibiting the procreation of people with inferior genetic attributes (euthanasia).
- the unconditional enslavement and consumption of anything, flora, and fauna, to benefit humans (predatory specieism).
Ethical or moral considerations of any kind would only take place insofar they'd be absolutely necessary to ensure humans' well-being.
tl;dr - the "objectively best" society an AI would build, would probably be a dystopian nightmare rather than a utopian paradise.