Wearing my WG co-chair hat, I think the WG does not have consensus on what to do. Further, it is not clear that we need to do anything other than be explicit about punting. That is, we don't have to say all the things we argued about and why.
I propose the following paragraph for the entire contents of section 13; comments are welcome.
All instances of publishing Atom Format entries SHOULD be protected by authentication to prevent posting or editing by unknown sources. The type of authentication used is a local decision made by the server and the client. Because of this, servers and clients are likely to face different types of authentication schemes.
--Paul Hoffman, Director --Internet Mail Consortium
