I still don't think it's enough. Then you just figure out who the fiduciary is and kidnap their kid instead. It's gotta be something where the coins are useless once stolen because you can't fake a convincing enough history for anybody to risk touching them. And not because maybe the cops show up, but because the recipient is equally concerned about finding people to accept their coins. The value of a given token has to be tied to the acceptability of its externalities such that a theft is just a destruction of value, not a reappropriation of it.

Or at least that's the only way I can see it working. It's gotta be based on consent, not scarcity.