It appears that he at least comes very close.
In reference to statements contained in the documents of Vatican II regarding “Religionsfreiheit, Judentum und Menschenrechten” (religious freedom, Judaism and human rights), this is what he said, in German: “Die kann man nicht ablehnen, ohne den katholischen Glauben zu beeinträchtigen.” In English, this literally means, “one cannot refuse without compromising the Catholic faith.”
Is he saying that one cannot hold the Catholic faith if one rejects the Vatican II statements regarding religious freedom, Judaism and human rights, statements that are contrary, or at least appear to be in their ambiguity, contrary to the teachings of the previous Magisterium? It would appear that is indeed what Müller is saying. Is he saying that these Vatican II innovations are de fide teachings, or teachings that are revealed by God and require the unconditional assent of faith by all men? He states that they have “dogmatic implications” (dogmatische Implikationen), so he appears to fall short in stating overtly that they are dogmatic in nature.
However, can a teaching that cannot be rejected without compromising the Catholic faith be logically anything other than a de fide, dogmatic, teaching? It would be a stretch, to say the least, to hold that such a teaching is not, indeed, de fide, but it is not impossible. Not all things that must be believed are necessarily dogmatic teachings of the Catholic Church, that is articles that have been formerly defined infallibly. We accept this without question since obviously the truth that God is Trinity had to have been believed by Christians long before the Council of Nicaea dogmatically defined it.
But the problem here is, once again, one of ambiguity, and this is what is at the heart of the Traditional Catholic critique of the Second Vatican Council. Allow me to demonstrate.
The innovations of the Second Vatican Council regarding religious freedom, ecumenism, etc. have not, it cannot be denied, been infallibly defined as dogmatic and de fide teachings of the Catholic Church, but yet prelates like Archbishop Müller insist that they must be held. It would be one thing if these innovations existed in a void of prior silence from the Magisterium, but they don’t. In fact these innovations that, according to Müller, “cannot be rejected”, must be held in contradistinction to traditional teachings that seem to be contrary to them. Not only that, but the Second Vatican Council fails to repudiate these prior teachings, and explicitly states the traditional teachings are still to be believed (“Therefore [the Second Vatican Council] leaves untouched traditional Catholic doctrine on the moral duty of men and societies toward the true religion and toward the one Church of Christ” Dignitatis humanæ, no. 1).
Thus prelates like Müller would like the Catholic in the pew to refuse to reject non-dogmatic innovations that appear contrary to prior teachings that have not been repudiated and must still be believed, and at the same time to hold that the innovations, while lacking dogmatic definitiveness, are de fide, nonetheless.
Archbishop Müller and his fellow “Vatican authorities” have jettisoned Blessed John Henry Newman’s primary thesis at the heart of his Development of Doctrine, namely, that development of doctrine is always a movement, effected by the agency of the Church’s Magisterium, from lesser to greater clarity in regards to what the Church has always believed. It would seem that the modern "Vatican authorities" have taken the Magisterium to be an elite club of speculative theologians, whose sole job is to garner the admiration of us ignorant peons, admiration for their academic fecundity and intellectual brilliance. We, the ignorant, sweating masses, are to accept without question the authorities' equivocations, and to accept the claim that something cannot be contrary or contradictory for the sole reason that they, the brilliant Vatican elites, say it cannot be contrary or contradictory. There's more pride than service about these "Vatican authorities".
The teaching office of the Catholic Church does not exist so a group of elite theologians with cardinal piping and hats can fiddle away their time indulging in speculative theology while strolling through the Vatican gardens. The Magisterium’s teaching office exists for the sake of charity. God’s people are supposed to be given the truth in an ever more clearly presented fashion by the Church’s Magisterium as it expounds the doctrines taught by Christ and defends those same doctrines from error. This is so the people of God might know with certitude what they must believe and what they must do to gain eternal life with God in heaven. Ultimately the Magisterium exists for the salvation of souls. If our modern churchmen refuse to present the Church’s teachings clearly, if they fail to defend them against error, they fail in charity, and they fail in the salvation of souls.
Müller would like all Catholics to accept his theological authority, but he demonstrates little or no regard for charity or the salvation of souls. He doesn't seem to be interested in defending or expounding the Church's doctrine. Rather, he seems to be just another mouthpiece for the post-Conciliar confusion. This certainly does not bode well for the Church that the new head of the CDF is more interested in spreading the confusion than in safeguarding the integrity and the clear transmission of Catholic doctrine.