Perhaps, but we already know that most people (and groups) are not Friendly

Not clear what you refer to by "Friendly" (I think this should be tabooed rather than elaborated), no idea what the relevance of properties of humans is in this context.

Making them more powerful by giving them safe-for-them genies seems unlikely to sum to Friendly-to-all.

I sketched a particular device, for you to evaluate. Whether it's "Friendly-to-all" is a more vague question than that (and I'm not sure what you understand by that concept), so I think should be avoided. The relevant question is whether you would prefer the device I described (where you personally get the 1/Nth part of the universe with a genie to manage it) to deleting the Earth and everyone on it. In this context, even serious flaws (such as some of the other parts of the universe being mismanaged) may become irrelevant to the decision.