Maybe he's a genius and solved distributed Byzantine generals with a single light bulb and majority voting?
The byzantine generals problem doesn't apply when you have trusted entities.
Except for the minor detail that you never do.
Perfect solutions do not matter.
The only thing which matters is good enough solutions.
For a state (i.e. most states in the current world) federated validators are good enough.
And systems which go beyond that (wrt. byzantine generals problem) have properties states tend to not want.
(I'm not judging if it's ethical good or bad.)
Let me make a different point:
I mean think about it for "legal" (legal unrelated to ethical) use-cases a federated systems of banks and maybe some external non-bank validators is good enough, by far.
Not "legal" use-cases are not legal and as such them not being supported is in the interest of the state you use them in.
Many of ethical good use-cases of crypto currency are not "legal", ethical yes but not legal anyway.
Like circumventing suppression in totalitarian states.
The problem is for each state by themself a "Byzantine considering" crypto currency is not in their interest. It can be use-full to help people in totalitarian states, but then this states can also use it to help extremist groups in your state while forbidding crypto currencies internally. So... not necessary the best choice.
Now federated not fully "Byzantine considering" crypto currencies are a different thing altogether. Like use bitcoing but replace PoW with PoS except the validators are predetermined banks with most in your country (or union like the EU, they might still stack money as collateral) and from a state view the problems are mostly gone/manageable (from a legal/state POV) and you get most of the technical innovation you want (I mean it is 99% the same tech minus "Byzantine considering" and maybe minus some privacy protections).
Now I'm not saying it's ethical good (or bad) for states to ban crypto.
But I am saying that from a purely objective non-ethic-considering view for most states it's best to just ban fully "Byzantine considering" privacy protecting crypto.