From what I could skim through the articles linked they are implying St. Thomas Aquinas is infallible because Trent, they assume, used some quotes from Aquinas. We are not bond to who a Council quotes but what a council says/writes.
Even so St.Thomas said that True Faith is absolutely necessary for salvation. As seen above SSPX say that True Faith is not necessary.see link Post 12
The belief in the the dogma Trinity and Incarnation is absolutely necessary for salvation for all those above the age of reason as taught by St. Thomas Aquinas, Pope Benedict XIV and Pope St. Pius X:
St. Thomas Aquinas, Summa Theologica, Pt. II-II, Q. 2., A. 7: “After grace had been revealed, both the learned and simple folk are bound to explicit faith in the mysteries of Christ, chiefly as regards those which are observed throughout the Church, and publicly proclaimed, such as the articles which refer to the Incarnation, of which we have spoken above.”
St. Thomas Aquinas, Summa Theologica, Pt. II-II, Q. 2., A. 8: “And consequently, when once grace had been revealed, all were bound to explicit faith in the mystery of the Trinity.”
Pope Benedict XIV, Cum Religiosi (# 1), June 26, 1754:
“We could not rejoice, however, when it was subsequently reported to Us that in the course of religious instruction preparatory to Confession and Holy Communion, it was very often found that these people were ignorant of the mysteries of the faith, even those matters which must be known by necessity of means; consequently they were ineligible to partake of the Sacraments.”
Those above the age of reason must believe as a** “necessity of means” **– cannot be numbered among the elect, as Pope St. Pius X confirms.
Pope St. Pius X, Acerbo Nimis (# 2), April 15, 1905:
“And so Our Predecessor, Benedict XIV, had just cause to write: ‘We declare that a great number of those who are condemned to eternal punishment suffer that everlasting calamity because of ignorance of those mysteries of faith which must be known and believed in order to be numbered among the elect.’”
** Response of the Sacred Office to the Bishop of Quebec, Jan. 25, 1703 (Denzinger #1349a):**
“Q. Whether a minister is bound, before baptism is conferred on an adult, to explain to him all the mysteries of our faith, especially if he is at the point of death, because this might disturb his mind. Or, whether it is sufficient, if the one at the point of death will promise that when he recovers from the illness, he will take care to be instructed, so that he might put into practice what has been commanded him.
“A. A promise is not sufficient, but a missionary is bound to explain to an adult, even a dying one who is not entirely incapacitated, the mysteries of faith which are necessary by a necessity of means, as are especially the mysteries of the Trinity and the Incarnation.”
Another question was posed at the same time and answered the same way.
(Denzinger 1349b) [catecheticsonline.com/SourcesofDogma14.php ]("http://www.catecheticsonline.com/SourcesofDogma14.php")
** Response of the Sacred Office to the Bishop of Quebec, Jan. 25, 1703:**
“Q. Whether it is possible for a crude and uneducated adult, as it might be with a barbarian, to be baptized, if there were given him only an understanding of God and some of His attributes… although he does not believe explicitly in Jesus Christ.
“A. A missionary should not baptize one who does not believe explicitly in the Lord Jesus Christ, **but is bound to instruct him about all those matters which are necessary, by a necessity of means, **in accordance with the capacity of the one to be baptized.”
As far as I know SSPX say that True Faith is not necessary which is not supported by either the BOD or the Strict traditions.
I am not saying who is right. I am only pointing out that the strict is ACCEPTABLE.
BTW: The three Feeneyite groups are in a better canonical situation than SSPX even after the lifting of the excommunications.SSPX is still not in FULL union as far as I know with the Vatican, but 3 of the 4 Feeneyites groups are in FULL communion with the Church.