Benedict XVI did not resign the "munus." He resigned the "ministerium."
The word "munus" can be translated as "office" but in the context of the Pope, another translation should be considered. Theologically and liturgically, the latin word "munus" means "gift," as in "the gift of the Holy Spirit" which is discussed on
Pastor Aeternus as the reason for Papal Infallibility.
We teach and define that it is a divinely-revealed dogma: that the Roman Pontiff, when he speaks ex Cathedra, that is, when in discharge of the office of Pastor and Teacher of all Christians, by virtue of his supreme Apostolic authority, he defines a doctrine regarding faith or morals to be held by the Universal Church, by the divine assistance promised to him in blessed Peter, is possessed of that infallibility with which the divine Redeemer willed that His Church should be endowed for defining doctrine regarding faith or morals: and that therefore such definitions of the Roman Pontiff are irreformable of themselves, and not from the consent of the Church.
The Pope is not infallible because he was elected by some Cardinals to be Pope. The Pope is infallible because of the divine assistance or gift, the word is
munus in Latin or
charisma in New Testament Greek.
Pastor Aeternus uses all of those terms in different places when referring to the special power possessed by the Successors of St. Peter. Put another way, we do not follow the Pope because he happens to be the highest human authority on earth, we follow the Pope because Jesus has promised that he cannot err on questions of faith and morals when speaking
ex Cathedra. Jesus never breaks a promise.
So, Benedict did not renounce the "munus," the "charisma," the gift of the Holy Spirit. As he said, he "remains in the enclosure of St. Peter." Only one man alive on earth possesses the "munus," the charisma. If Benedict did not renounce it (and he did not), then he retains it. Therefore, Benedict XVI and only Benedict XVI is infallible regarding pronouncements on faith and morals. Bergoglio is a usurper and a destroyer. Don't let this SSPX analysis confuse you.