Relativism
We let the super-intelligent "Minds" decide how to execute policy, with the possible exception of going to war. As to what policy should be, yes, there will always be disagreement, but ideally the mantra would be "if you think you'd be better off in a different system, don't interfere with those who don't, or go elsewhere."
Both of these would only be optimal or even possible in a society that lacked serious cultural/moral heterogeneity and had done away with money, poverty, illness... I think perhaps you're thinking more about the here and now, when I'm thinking more abstractly about the (distant) future.
(I think my point is far more abstract that you seem to think it is!)
Which God decided that "intelligence" (regardless of how high) is a required criteria for deciding benevolence? Would they have a better idea about how someone would want to be treated than that person themselves, for instance. Again, it's all basing it on ultimately arbitrary criteria.
I would think it would be more like this: each individual who opts to live in this "benevolent regime" would essentially decide however to live their own life, under the guiding principle that "my right to swing my fist ends where the other man's face begins." Ultimately you can't make everyone happy, so those who simply cannot abide this regime would be forced to leave it.
These criteria are arbitrary. It's arbitrarily an anarchist-communist utopia based on hedonism. However, I believe that under that arbitrary system the most benevolently righteous regime would be able to function, i.e., that is the best form of society.
I can't justify this point of view scientifically or logically, because doing so would require too many a priori assumptions. Why is intelligence necessary to make good policy? I suppose you could get lucky, but that's not a government I would put much faith in.
This is a world much like an projected Lumenosian afterlife, called the Meif. Meif means max initial equal freedom. "People" interact in worlds wherein the physics are decided by contract beforehand. One of the possible problems is the inability to redeem the lost soul. The bad people try to entice people into contracts wherein they end up enslaving themselves. Some may end up in one of these hells by their own decision.