I think you're misunderstanding Red's contention here.
If I understand correctly, it's not that proof of work is unnecessary if you want to reach consensus on transaction order without trusted bookkeepers.
Rather, it's that having trusted bookkeepers isn't so bad.
So, basically, Red wants to make MtGox into the new Rothschilds, and revans says that early adopters are already them.
MtGox is undoubtedly the central bank of Bitcoin already, and they engage in the kind of price fixing activity central banks always do