It’s less about the separation of powers and more about the fragmentation of each power. As in, you should be able to ditch any governing power that you dislike, and curb down its influence on your experience to a bare minimum.

I said separation of powers because you said the Fediverse should be like a democracy. Then it should have that. For me, democracy is first of all a better way to control those in power, which is why I think we shouldn't think of the Fediverse as a democracy, because it isn't; at least not currently. It's not like you have a say in the general development of the Fediverse, because there is no real centre to it anyways.

So, I agree with you here, I just don't think that's what a democracy is. If the Fediverse would be a democracy, it would have government, a constitution, etc.

But as I said, I agree with you how we should think of the Fediverse: as acephalous. However, why should it be completely acephalous? Why shouldn't servers make agreements with one another? The Fedipact is one of those, the badspace, too. And while I'm not a fan of the first one, its generally fine, if they don't force people into it (like you said). Why then not try to do the same thing but with some actual principles?

What happens if said commitee becomes hostile, defending its own self-interests in detriment of the ones of the rest of the Fediverse?

Then many servers will opt out of it and it will become irrelevant. That's the beauty of it. Because its only an agreement that is not controlled by any centrlized entity, its not as binding. The same as with the Fedipact: it wasn't set up by any central entity and will not be enforced by it other than the community or powerful servers. But that the community and powerful servers will try to influence the course of the Fediverse is the the case anyways!

And the ones screwing up on moral matters get isolated.

For Nazi-instances, that's easy, but for example in the case of Threads, it quickly becomes very complicated to agree on which instances should be isolated and which not. How do you determine that if not through speaking to other servers? And if you do that, you can just as well speak to them about common rights and write them down somewhere. It's the same thing but with more transparency.

We cannot build the Fediverse without trust and mutual agreements. It will just not work; and we are also already doing it.