The argument is that the traditional Latin Mass, in the 1962 version of the Mass of Pope Saint Pius V, cannot be abrogated. Taylor Marshall: “No Pope can abrogate the traditional Latin Mass.”
It’s in Summorum Pontificum, they say: “What earlier generations held as sacred, remains sacred and great for us too, and it cannot be all of a sudden entirely forbidden or even considered harmful.” That’s actually from the Letter that accompanied SP, but in any case, Benedict wrote it.
The problem is that this assertion is not dogmatic, nor even a non-infallible teaching. And other Popes have said things that might allow the Latin Mass to be replaced by the Novus Ordo.
1. Pope Francis holds that the Novus Ordo is the continuation of the ancient liturgical tradition. So there is no abrogation, if you think that abrogation is impossible.
“Whoever wishes to celebrate with devotion according to earlier forms of the liturgy can find in the reformed Roman Missal according to Vatican Council II all the elements of the Roman Rite, in particular the Roman Canon which constitutes one of its more distinctive elements.” Letter accompanying TC
The Old Covenant was never abrogated; it was transformed into the New Covenant. The old Latin Mass need not be seen as abrogated, but rather transformed into the Novus Ordo. That view will not satisfy supporters of the TLM, but it is a position that can be taken. I don’t know if I agree with that or not. I’m still reading and considering the topic.
2. Pope Pius XII
See this article. There are lengthy quotes from Mediator Dei. They clearly refute the claim that the Mass established by antiquity is therefore irreformable, unchangeable, or is established as a right that the Pope and Church cannot remove.
3. Full Authority
It is a dogma that each Pope has the same full authority given to Peter and his successors. If one Pope, such as Pius V, could make a decision of discipline and bind future Popes to that decision (or in this case a set of decisions) then future Popes would have less authority. And if every Pope could bind future Popes, each one making binding decisions of discipline, then the authority of successive Popes would ever decrease. Since this is contrary to the dogma that every Pope has supreme, full authority, it cannot be the case that the Mass of Pius V is established as binding on future Popes.
It also cannot be the case that Pope Francis’ decision is binding on future Popes either. He can abrogate the Latin Mass, but his successor can revive it.