The failed utopia is better than our current world, certainly. But the genie isn't Friendly.

In principle, I could interact with the immoral cluster. AI's interference is not relevant to the morality of the situation because I was part of the creation of the AI. Otherwise, I would be morally justified in ignoring the suffering in some distant part of the world because it will have no practical impact on my life. By contrast, I simply cannot interact with other branches under the MWI - it's a baked in property of the universe that I never had any input into.