This whole thing relies on users to essentially enforce the trust web. No way this works in reality. Eve won’t try to establish trust with Bob directly. She’ll

This whole thing relies on users to essentially enforce the trust web. No way this works in reality. Eve won’t try to establish trust with Bob directly. She’ll establish trust with Bob’s grandmother who doesn’t know any better. She’ll essentially phish her way into the trust network. After convincing Grandma to accept a single EveCoin, Grandma will perform any currency exchange for Eve and let Eve buy whatever she wants with BobCoins. When your premise is that “it is crucial that users take direct peer-to-peer trust relationships seriously”, you are doomed to fail. You cannot expect security to derive from the average person being extremely diligent.