I disagree, and believe theologians have used temporal universality as a necessary criterion to distinguish true from false teaching going all the way back at least to the 5th century (eg., St. Vincent of Lerrin’s famous Commonitorium):
Yes, the time criterion seems a bit uncertain to me. If you say that the "universality in time" argument is essential, this leads to problems.
It implies that at any given time the Magisterium could go off the rails and cease to be a reliable guide to truth and can even actively lead people into error ... which seems to contradict the indefectibility of the Magisterium.
Also, there are some striking counter-examples. So, for instance, since St. Augustine through about the year 1100, all Catholic theologians held that unbaptized infants went to hell, and that was later corrected by the Magisterium. Also, for the first 1600 years, all Catholics believed and taught that those without explicit faith in the Holy Trinity and Incarnation cannot be saved. But then some Jesuits started to innovate, and it's not been officially condemned by the Church.
Articles dealing with the OUM admit that it can be nebulous in terms of what belongs to the OUM and what does not, and that ultimately for Catholics to know for sure that something is dogma of the OUM, the Church would have to define it ... at least to make it clear.
So, Sean, my issue with R&R is that I simply cannot see how a major going off the rails of the Magisterium for 60+ years could in any way be consistent with the promises of Our Lord to preserve the Magisterium as a reliable source of the Catholic faith.
If telling people that they MUST REJECT the Magisterium (or large parts of it) in order to please God and to save their souls, then, if that isn't a defection of the Magisterium, then I have NO IDEA what would be.
That's really the big dispute between R&R and sedevacantists. R&R hold that a vacancy of 60+ years is incompatible with indefectibility, whereas the sedevacantists hold that a corruption of the Magisterium and Universal Discipline of the Church is a much bigger problem with indefectibility.
Here's from the Catholic Encyclopedia:
Among the prerogatives conferred on His Church by Christ is the gift of indefectibility. By this term is signified, not merely that the Church will persist to the end of time, but further, that it will preserve unimpaired its essential characteristics. The Church can never undergo any constitutional change which will make it, as a social organism, something different from what it was originally. It can never become corrupt in faith or in morals;
Is the Conciliar Church not "corrupt in faith or in morals". It's corrupt in both. It's corrupt in its public form of worshipping God.
So the R&R are focused on the "persist to the end of time" while sedevacantism considers this large-scale corruption of the Church to be a bigger problem, feeling that a long-term vacancy of the See is compatible with that persistence of the Church to the end of time.