Because the Archbishop didn't understand previous teaching. The most obvious example is religious liberty - he misinterprets Quanta Cura and ignores Pius XII. Collegiality is another - he rejected it even though it's in conformity with the previous magisterium.
Again, the Assisi event was a private action of the Pope - not an act of the Magisterium.
It is true that one notes differences of opinion and theological formation among the prelates of the Church; however, a simple sentence, even said by the Sovereign Pontiff, is not an act of the magisterium; we know that all statements assume different degrees of authority. It is always possible to criticize this type of statement, as well as a style of governing. The criticism, however, demands an authentic understanding of the thinking of the other person, and should presuppose that he also possess the Catholic faith. If one raises inconsistencies, the criticism, made with humility and charity, becomes a service rendered with great respect and in a spirit of sincere collaboration. (Cardinal Hoyos, Letter to Bishop Fellay)
"Because the Archbishop didn't understand previous teaching."
Give me a break. You hang everything on Religious Liberty as if that explains the break between the SSPX and Rome. One can easily counter with the fact that the Pope did not understand Trent--or the Syllabus of Errors, for that matter. It was the whole idea of revolution which Lefebvre opposed, beginning with a Liturgy which deliberately subverted Catholic dogmas and ending with Assisi which flagrantly affirmed the most radical and heretical form of indifferentism and syncretism ever experienced within the walls of the Catholic Church.
And when you couple all this with the breakdown in discipline on the part of this Pontiff, a breakdown which selectively punished the Archbishop's for his adherence to the ancient faith, yet tolerated every other clerical blasphemy and desecration and corruption humanly conceivable, then you see there is some need for us to draw back and reconsider just how much we owe the Pontiff himself and how much we owe to the Catholic faith. Because the two are at times irreconcilable and no man can serve two masters. Either we must follow the Pope and his revolution--or we must follow the traditional faith.
"however, a simple sentence, even said by the Sovereign Pontiff, is not an act of the magisterium; know that all statements assume different degrees of autwe hority. It is always possible to criticize this type of statement, as well as a style of governing. The criticism, however, demands an authentic understanding of the thinking of the other person, and should presuppose that he also possess the Catholic faith. If one raises inconsistencies, the criticism, made with humility and charity, becomes a service rendered with great respect and in a spirit of sincere collaboration."
Funny how suddenly not everything is a magisterial teaching when it suits the Vatican to draw back from the brink. In Ecclesia Dei the Pope is insisting on the "Living Magisterium" as cover for his novelties. --Yet here is one of his cardinals, when called on it, suddenly making it clear that all statements "assume different levels of authority." In other words, the Pope now and then gets it wrong. Fine. At least this is honest. But what is this except what has been argued by the SSPX all along--that not everything the Pope says and does is authoritative, especially the motu proprio? You only agree to this when it suits you, when you want to wriggle out of an embarrassment like Assisi. But you can't. Why? Because had any other prelate on the face of the earth done what he did, it would not really matter. But the Pope, by his very act, made Assisi a huge issue. It spoke volumes about his lack of traditional sensibilities. It is not every day a Roman Pontiff defies the entire history of his Church and the First Commandment itself to push his agenda. The attempt by Hoyos to dismiss this is futile--it speaks for itself and is at the heart of the present war between the revolution and Tradition. We are right to ask ourselves--which man lacks the true Catholic sensibility--a man like the Archbishop who followed the ancient ways and teachings--or a Pope who worships with witchdoctors?