As a "Traditionalist," dead excommunicated Marcel was on a par with "Pope Michael" of North Dakota and other loons of that ilk. No one did evil to Marcel and his satraps. They got what they deserved from John Paul II and the survivors have so far gotten far better treatment than they deserved from B-XVI. In the Age of Faith, these miscreants would have been subjected to a just inquiry and burned at the stake. We live in gentler times and a good thing for them since it prolongs the period during which they may repent as publicly as they have revolted. If Pope St. Pius X were alive and had available the remedies of the Age of Faith, he would certainly burn these chronic malcontents and eccentrics at the stake for impersonating Catholics.
Blasphemy is against God. Popes are not God. They are however his vicars on earth. See Matthew 6:13-20. Roma Locuta Causa Finita.
You have the entire litany of SSPX rationalizations down pat but repetition does not enhance them to truth.
B-XVI noted that the Tridentine Mass had never been surpressed. Frankly, you could have fooled me but thanks be to God for JP II and Benedict. John XXIII and Paul VI made prudential errors and they are being corrected no thanks to the sulfuric rage of Marcel and SSPX and SSPX's ceaseless attacks on the Church. Fellay is still presuming to instruct the papacy on Catholicism (flea, elephant's leg, rape in mind). Has de Mallerais gotten control over his infernal mouth yet? Did Marcel die excommunicated and in schism? Were John XXIII, Paul VI, John Paul I and John Paul II popes or not? Did they have the keys or not? Were any of Marcel and his malcontents ever popes or not? Is Williamson still rampaging against history as well as against Catholic tradition or not?
As to non-Catholics (including SSPX?) having a "right" to embrace their religions, we Catholics have a name for it: free will. We are not Calvinists. We are not Feeneyites. We draft no one and we leave it to God to judge each person including ourselves. It is above our pay grade to substitute our judgments for His and futile in any event. Catholicism is a far easier glide path to heaven with all of the Mass, the sacraments and the races available to Catholics but God knows better than you and better than Marcel and better than me. Don't you think?
The only "crisis" experienced by Marcel and his mad hatters at the hands of the Vatican was that their infernal ids were stylistically offended to such an extent that they launched a rebellion against God's own Church and against his Vicars on Earth. Nothing new under the sun. There have been angry schismatics and heretics from very early on. The Church and the papacy survive them all as Jesus guaranteed. His guarantees are still good and always will be.
Whatever will you folks do when JP II is canonized and Pio Nono and even John XXIII? One of my favorites is Pope St. Gregory VII. I would also like to see Leo XIII and Pius XII canonized and JP II recognized as Saint JP the Great. A very god argument can be made for John Paul I to be canonized as well. Each in his own way resembles Pope St. Pius X. Marcel is about as likely to be canonized as is Alexander VI (Borgia). As to those two, don't hold your breath.
Marcel is a hindrance and not a help but we shall have our Mass back as the norm sooner or later and the sooner the better (which probably requires Fellay, de Mallerais, Willimason, Gallaraga and their minions to dry up and blow away). maybe the miscreants will go the way of the "liberation theologians," of Charles Curran, of Fr. Drinan, etc.
If you make it to heaven and find Protestants or Jews or popes of whom you do not approve there, will you ask God for permission to leave or just try to escape lest the Teaching Magisterium of Marcel and you be transgressed without your resisting God to His Face?
Ron Paul is not a conservative. Fred Phelps and Westboro Baptist are not Christians. Cindy Sheehan is no patriot. AND Marcel and SSPX are/were not faithful Catholics. In each case, absent public repentance, Burn 'em bright!