Every poster on this thread could likewise publish an exposition employing the same format as St. Thomas Aquinas, and each would carry the exact same magisterial weight as those you have quoted.
The logical weakness in the sedevacantist position remains. Those in the sedevacantist movement, having deserted the Barque of Peter, are left with only their personal judgment or that of their sedevacantist group or leader regarding the validity of a pope. Once they dare to arrogate to their personal judgment matters which properly belong to God (or perhaps to the hierarchy of the Church, although it’s unclear if even cardinals have the authority to depose a pope) it seems quite possible, and even likely, that only the Second Coming of Christ would induce them to return.
Not logical? Not nearly as illogical as claiming to recognize a true pope and yet decide which of their liturgies, disciplines and teachings they will obey.
Have a nice day Blather.