A site can be owned, or not. If it is owned we ask two simple questions "Who Are You?" and "Are You The Site Owner?". The separation of these two questions is important, as we will see.
Federated Wiki is only concerned with "Who Are You?", authentication, when the site is owned and you are performing an action that only the site's owner is allowed to perform.
My instinct is to make a big deal about Ownership. This needs thinking through. Security is traditionally separated from ownership, that is the author and the system administrator are different people.