In the short term we need a safe haven from Crypto, having a gold backed currency would be better than a fiat backed currency.
Any backed currency requires a trusted party and having a permissioned block chain is irrelevant as you need to trust 100% the people who are storing the backing.
Having a permissioned blockchain based on PoS means they can censor or undo any transaction, as long as enough of the stake agrees. Probably, the majority stakeholder could do that alone.