Luther claimed to be Catholic too and behaved in just about the same fashion as today's schismatics. He was no Catholic and neither are the SSPX people. If you think so much of Monsignor Perl, try to understand what he is saying: The Mass of an unworthy, defiant, disobedient, schismatic priest is still a Mass so long as his Holy Orders are valid (which no one ever doubted and I think I am a veteran critic of SSPX around here).
Donatism is still a heresy. And if SSPX is attacked for Donatist reasons, it is attacked for the wrong reasons when there are plenty of perfectly valid reasons to attack SSPX as the schism that it is. Perl was answering specific questions. He did not suggest that Catholics lie down with dogs or that they get up with fleas but rather that any Mass is better than no Mass on a day of obligation, even an SSPX Mass.
Since you think so much of the authority of Monsignor Perl, however, you should consider heeding his boss, JP II, and returning to the Faith.
Luther may appear to "have behaved in the same fashion as today's schismatics"--in your lexicon those evil wretches who attend SSPX Masses rather than deny the faith. Yet consider this: he BELIEVED exactly as the Novus Ordo crowd does today. His liturgy was virtually the same.
Two thirds of all Catholics no longer believe in the Real Presence. Why do you suppose this is? And why hasn't the Pope instituted clear measures to halt this erosion of Catholic belief? Why does he continue with World Youth rallies which only perpetuate this trend? Does he know about Sacred Hosts being dropped in the mud or swigged down with beer or soccer games being played while he speaks the words of Consecration? If he doesn't--should he? If he does, why hasn't he instituted more reverent practices? Isn't Jesus really and truly present in each Host? Am I missing something?
Luther was never excommunicated and died in the Catholic Church. Bugnini (the architect of the Novus Ordo) made the bold claim that the NO was more radical of a reform than either Luther or Calvin envisioned.