Actually, the issue hasn't been understood correctly. Dogmatic fact not only establishes that the Roman Pontiff currently possesses supreme jurisdiction in act over the whole Church Universal, but moreover, when it is verified, it is an infallible sign that he is the currently reigning Bishop of Rome. This appear in the Theologians which Resistance Types and Sede-Vacantists have read, but not read carefully enough. E.g. "[Dogmatic facts] include things of this sort: that the Sacred Scrip- tures we use are genuine; that the Councils of Nicaea, Ephesus, Trent, etc. were legitimate; that Pius IX, Leo XIII, etc. were elected legitimately and consequently were legitimate successors to Peter as Bishops of Rome. Just see what would result if you would let any of these things be called into doubt. Defini- tions issued during Councils would not have certainty. There would be no sure way of determining the center of Catholic unity. In short, what would result is the uprooting of faith itself and the destruction of Rev- elation."
http://www.catholicapologetics.info/modernproblems/currenterrors/sifting.htm#_ftn9 Yes, well said, Ladislaus. That was his article. The citation is from Fr. Hunter, in Compendium of Dogmatic Theology, a text we've independently seen on this forum before also. And there are other Theologians who state this as well, not only regarding Papal Jurisdiction, but their having known to have become Bishops as well. Now, here's how the Syllogism would go, once the 2005 election transpired and the Papacy of Pope Benedict XVI became a dogmatic fact - by this fact itself, independent of all other considerations, it necessarily follows as a mutually interconnected dogmatic fact that Pope Benedict XVI was the validly reigning Bishop of Rome.
Major: Pope Benedict XVI's election became dogmatic fact in 2005 so that he was known to be reigning as Pope.
Minor: One currently known to be reigning as Pope must not only be in possession of jurisdiction but orders also.
Conclusion: Therefore, Pope Benedict XVI's election, post 2005, also proved infallibly that he was a valid Bishop.
Corollary: Therefore, after 2005, all doubts must cease or become heretical. The new rite is now infallibly valid.
This is why Rev. Fr. Pierre Marie's study, from the Dominicans of Avrille, was both Providential and timely. It was pubished in 2007 I believe.
In Pope Benedict XVI's Papacy, after more carefully examining the evidence from Eastern Tradition, the issue was settled even otherwise.
But this one consideration alone is sufficient. A man has been elected Bishop and received consecration. He has been accepted as Her Archbishop both by the Roman Church and as the Archbishop of the Roman Archdiocese or Roman Pontiff by the Universal Church. He certainly possesses the supreme jurisdiction in act, and is now infallibly known to possess valid orders as well - such that it would now, after the Teaching Church's judgment in accepting his election, be heretical to doubt that the new rite is valid.