Suffice to say in response to all your questions and accusations, Ladislaus, that it is not puerile to follow in these matters the prince of the Church that God gave us. Nothing has substantially changed since the time of Archbishop Lefebvre, and there is no certain reason for us to change direction guided by the Catholic principles that he so clearly enunciated.
No, what I was referring to as puerile is this dispute about the competing claims that this group or the other group are the "true heirs" of +Lefebvre. As for "following" +Lefebvre's "principles that he so clearly enunciated," apart from some core tenets that he always held to, with regard to the question of SVism vs. R&R, there was absolutely nothing "clear" about them, nor was he consistent over the years. During the early 1980s, the things he was saying could have been uttered by +Fellay a couple years ago. By the mid-1980s, he said that he might have to become an SV due to Wojtyla's activities. What, then, would he say about Bergoglio's activities, which make Wojtyla look like St. Pius X by comparison? Nothing "substantially changed" either between the early 1980s and the mid-1980s, and yet +Lefebvre changed his mind.
+Lefebvre repeatedly stated that SV is a legitimate theological position (citing St. Robert and others who discussed the matter) IN PRINCIPLE, but questioned whether it applied to the case of Wojtyla. So the difference isn't in the principle, which he consistently agreed was viable, but about its application. How would he have applied it to the case of Jorge Bergoglio?
Now, one of "the Catholic principles that [+Lefebvre] so clearly enunciated" was that the Papacy is guided by the Holy Spirit and that this degree of destruction is "impossible", i.e. inconsistent with that guidance by the Holy Spirit. This is one eminently clear "Catholic principle" that most of those who claim to be +Lefebvre's heirs have conveniently discarded. +Lefebvre's only hesitation was in coming up with the exact explanation for how all this happened, and also in deferring to the final judgment of the Church. But he came a hair's breadth from coming out publicly as sedevacantist when confronted with the abomination that was Assisi. And who's to say that he would not have done so in the case of Bergoglio?
Bottom line is that the PRINCIPLES of +Lefebvre were mostly (except in the early 1980s) open to the possibility of SVism and the difference was in their APPLICATION to the concrete situation and concrete scenarios. Since he's no longer around to apply his principles to the case of Jorge, we have no idea where he would have gone. Would he have gone Bennyvacantist? sedevacantist? sedeimpoundist? We don't know, so we have to stop treating +Lefebvre as though he's 1) some rule of faith and, what's more, 2) some LIVING rule of faith (since he's no longer alive).
Archbishop Lefebvre was a great man, but still just a man ... and he made some mistakes, especially with regard to practical judgment (appointing various SSPX leadership ... +Fellay, Schmidberger, and numerous others), and in some cases with regard to theological issues (where he adopted and promoted Rahner's "Anonymous Christian" soteriology). I believe he was mistaken in expelling The Nine also, since at the time he was of the "practical agreement" mindset that +Fellay later adopted.