If I were to become entirely convinced baptism of desire is actually heretical, I would have no other choice but to declare Pope Pius XII to be a heretic who ipso facto lost his office (or never had it) without need for any further declaration. Even Br. Dimond says that if Pope Pius XII had personally signed the Holy Office letter, he would be a heretic. Therefore, the only two possibilities are (1) Pope Pius XII is a heretic (2) baptism of desire is not heretical. Tertium non datur (there is no third option). Pius XII's holy office clearly said in the letter quoted earlier that denying bod is "very harmful both to those within the Church and those without". Also, Pius XII taught the same doctrine as the holy office letter in other places. For e.g. he said: "In an adult an act of love may suffice to obtain him sanctifying grace and so supply for the lack of Baptism". So do any other sedevacantists want to go that far, that Pius XII was also a heretic just like John XXIII and Paul VI were?
Again, Fr. Feeney should have gone to Rome. Archbishop Lefebvre went when Rome summoned him. Even Our Lord Jesus Christ went before Pontius Pilate to testify to His Gospel. If Fr. Feeney was genuinely convinced, as some of his followers here believe, that Pope Pius XII would have supported him, and that it wasn't the Pope, but only Archbishop Cushing, and also at least Cardinals Selvagianni and Ottaviani (who signed the letter) who were teaching BOD, he would have gone to Rome and clarified the matter. In fact, this would have been an exceptional opportunity to present the Gospel and the Catholic faith before the Roman authorities. This is the reason Fr. Pagliariani also gave recently for discussion with the Roman authorities. Even if Rome were not 100% convinced by the Society's theological arguments, it was an excellent opportunity to present the Gospel (i.e. the orthodox Catholic faith in its fullness) to the Roman authorities.
So I think Fr. Feeney missed a golden opportunity. Next, here is Fr. Fenton explain that Suprema Haec Sacra is indeed authoritative Magisterium, ordinary Magisterium about which Pope Pius XII says, "these things are taught with the ordinary teaching authority, about which it is true to say, "he who hears you, hears Me". Thus, again, if Pius XII was a Pope, it is Christ Himself whom we hear to teach us bod. Thus if bod is heretical, it clearly follows that Pius XII was every bit a heretic as Paul VI and John XXIII and therefore either never pope or ipso facto losing office for bod.
Fr. Fenton: "One of the few good results that followed from the unfortunate debates centering around Father Feeney's group at St. Benedict's Center was the issuance of the Holy Office instruction Suprema haec sacra, dated Aug. 8, 1949, and published officially with its authorized English translation in the Oct., 1952, issue of The American Ecclesiastical Review. This docuмent made it very clear to the men of our own time that the Church had by no means abandoned or modified the age old dogma to the effect that there is no salvation outside of the Catholic Church. As a matter of fact this Holy Office letter put the magisterium itself on record as asserting what had been, since the latter part of the sixteenth century, the teaching of the best theologians of the Church: the doctrine that the Catholic Church itself is definitely and actually necessary for the attainment of eternal salvation with the necessity of precept and with the necessity of means."
https://tradicat.blogspot.com/2013/10/questions-about-membership-in-church.html The Church of course still teaches EENS. She just rejects the Feeneyite interpretation of it. Either that, or if the Feeneyite interpretation is correct, the Church defected at this time by teaching heresy. That's if Pius XII is a legitimate Pope.