... which he so freely labels them, but we would be faced with the ridiculous situation of just about every theologian after Pope Martin V, who continued to discuss the issue of how a heretic is deposed, being heretics also. Absolutely absurd!
Where Brother fails here is that he keeps falsely attributing to sedeprivationists the notion that public and manifest heretics remain (full) members of the Church. In all but one clip, where Father Desposito slipped (and obviously English is not his first language) and said that they were not "manifest" until declared by the Church, something which sedeprivationists do not hold, in all the other clips, they refer to their LEGALLY remaining in possession of the office.
Unfortunately, Brother ends up attacking a strawman by equating sedeprivationism with the Salza & Siscoe opinion, which Fr. Desposito's slip-up, unfortunately, allowed them to do.
Recall St. Robert Bellarmine's enumeration regarding the requirements for full membeship in the Church :
1) Sacrament of Baptism and ongoing communion in the Sacraments
2) Profession of the True Faith
3) Subjection to and union with the Supreme Pontiff and the Catholic hierarchy
Manifest/Public heretics fail #2 and therefore are not full members of the Church. It's possible, however, that they remain in Communion (#1) without having been excommunicated, and in union with the hierarchy (#3) not having yet been deposed.
So there's nothing wrong with saying that these men remain in LEGAL possession of their office, which is what Bishop Sanborn et al said, except for that one statement by Father Desposito. He's most certainly wrong that a declaration is required to be a "manifest" heretic. Pope Martin V most certainly put that to bed, and put a nail in Salza's coffin. But that's not actually what most sedeprivationists hold.
Pope St. Celestine refered to the state of Nestorius after he became a manifest heretic (i.e. began preaching heresy) as being that of an "excommunicandus" (someone who should / needs to be excommunicated). This implies an in-between state, where one is not fully excommunicated but SHOULD be excommunicated on account of manifest heresy. In this state of "excommunicandus," Nestorius had no power to excommunicate others, depose them from office, or of course preach his heresy.
Pope Martin V also alluded to an in-between state where they were public/manifest heretics but yet not officially deposed or removed from office.
Take the concrete case of Cardinal Cushing of Boston. Clearly a manifest heretic if ever there was one. "No salvation outside the Church? Nonsense." (one could go on for hours about Cushing's heresies). In any case, let's accept that he was just for the sake of argument. Even though Cushing was a public / manifest heretic, he was not deposed by Rome and considered by Rome to be in possession of the office, and in that role he continued to transmit jurisdiction (as a conduit from the Holy See) to the priests in his diocese, who had through him the faculties to hear confessions. Cushing remained in legal possession of the office despite having been a manifest heretic.
Does the fact that he was not condemned make him not a manifest heretic? No. Pope Martin V put that (the Salza opinion) completely to rest. But does that mean that his being Bishop of Boston meant absolutely nothing? No, that's not true either. He remained there by the designation of the Pope.
Sedeprivationism does not hold that these me are not manifest heretics. Father Chazal in his sede-impoundist position (very similar) concedes that they are in fact manifest heretics. Both both positions hold that they are in some in-between position, somehow suspended between the two, partly in and partly out, on the way out, impounded, and "excommunicandus".
It's unfortunate that Father Desposito slipped up and briefly articulated the Salza/Siscoe position.