That decree proves the point my previous post. Per Catholic theology, Benedict can't make any such statements, since he can't exercise the charism of an office he resigned from.
By way of analogy, I used to be a supervisor in a unit at my company. I voluntarily stepped down, but still work for the same company. Now there is new a supervisor of the unit. I can't now go to the unit and tell the employees what to do, since I gave up any authority I had there when I decided to step down. The authority now resides with the current supervisor.
Well, I think that
"When the Roman Pontiff speaks ex cathedra, that is, when in exercising his office as shepherd and teacher of all Christians he defines with his supreme apostolic authority that a doctrine on faith and morals is to be held by the whole Church, through the divine assistance promised him in the person of St. Peter, he enjoys that infallibility with which the divine Redeemer wished to endow his Church in defining a doctrine on faith and morals."
may perhaps still be true of ... well, you know, the man we're talking about; but the thing is, it's a conditional statement, and I'm sure that he has no intention of issuing any statements satisfying the conditions.
Per Catholic theology I believe the charism of papal infallibility is in the office of the Papacy, not the person. Since Pope Emeritus Benedict is now resigned/retired, the charism doesn't follow him, but would go to the next holder of the office.
Orrrrrr everyone should just calm down. I'm sure it will be just fine. Does anyone really believe that Pope Benedict has any intentions of causing problems for the next Pope or for the unity of the Church?
The problem is, I believe, that the 'special Charism' of Peter was already transmitted to Ratzinger on him becoming pope... and he's still alive. Does he 'cast off' Peter's charism?