Shouldn't it be Father Ratzinger? In the interests of avoiding confusion, that is.
Exactly. Or, if they want to be spread a little more of the modernist fairy dust, you could make the case for Father Joseph. I wonder if this was rejected, the name Father Benedict, because it is just one word shy of Holy Father Benedict.
Either way, I really can't stand the title Pope Emeritus. It drives me crazy when I hear it. Almost to an irrational level.