Off the cuff, I would suggest that this supports the "[traditional] Catholic clergy". Archbishop Thuc had enduring papal mandate, and Archbishop Lefebvre's position seems very reasonable given his position in the Church and experience at the council. In my opinion, Apostolic Succession was preserved through the crisis.
Jurisdiction, in this time of common error, is supplied by the Church. I would assume jurisdiction over the universal Church is precluded by the condition of sede vacante.
As St. Gelasius writes: "It is the papal responsibility to keep the canonical decrees in their place and to evaluate the precepts of previous popes so that when the times demand relaxation in order to rejuvenate the churches, they may be adjusted after diligent consideration." [Pope Gregory XVI, Mirari Vos, August 15, 1832.]
Yes, it is a documented fact that each of Archbishops Thuc and Lefebvre (and bishops de Castro-Meyer and Mendez Y Gonzales) went to great lengths to insure that far more than a mere materially valid succession would be transmitted to the bishops they consecrated for the good (and whole future) of the Church. The St. Gelasius quote is certainly a good one, and one which reminds us of something so basic that some have forgotten it.
The teaching of the Church is quite decidedly on the side of the apostolic authority of our familiar traditional clerics, for the alternatives are truly unacceptable, doctrinally speaking (Church no longer exists, Church hidden in an invisible manner within the Novus Ordo, Church existing only in unknown and remote "forgotten" corners of the earth which no one can find, Church relegated to what few areas an Indult or Motu "Extraordinary form" might be permitted, Novus Ordo apparatus as the Church in any sense, etc.)
The following document actually constitutes a "crash course" in all the relevant ecclesiological doctrines which despite the denials of some still apply to our age as they must indeed apply to all ages, no matter how difficult: http://www.the-pope.com/blog.pdf
I'd like to see if anyone else can come up with an ecclesiology which fits to the eternal ecclesiological doctrines, the recent and current historical facts (Vatican II, etc.), and can also explain how the Church still existed as a visible and Catholic society, bearing all four marks, throughout this whole period.