There are pros and cons to using formal structures. For example managing a bank account in the name of an association is easier and more trusted than someone’s personal account. My vision of the credit commons is an informal association, accountable only to its members, which does not handle money at all. This is how Bitcoin works. There is no association but anyone can install some free software and just plug into the network. Later the Bitcoin Foundation was created to help grow Bitcoin but many users didn’t regard the foundation as legitimate.
By contrast the credit commons would embody a similar libertarian ethic, but instead of being an open system without trust, it would consist of private groups who may or may or not trust each other. Thus anyone could open an account in a credit commons, but only trusted people and groups could exchange. In this arrangement I see no benefit to registering the credit commons as an organisation, since no money should change hands and no legal recourse is needed between trusted parties.