Unless the protocols by which trusted relationships can be created and destroyed are well-known, they can't be engaged in on a widespread basis. This is the equivalent of web browsers that don't support http, where each browser has its own protocol. The key point here is the notion of a trusted metamodel. Trust is a fuzzy thing, and so is the universal metamodel. Current RDF thinking is binary with regards to a statement.
Statements also extend into time and trust dimensions.
My metamodel should be different from yours. You could choose otherwise. That would be a body of law. I think there is a clever information-trust recombining algorithm waiting out there to be discovered. It is not obvious to me if there is a single best way to do it.