Does the pope speak from the Chair of St Peter when he says mass? Is he teaching dogmatically during mass? Of course not. You need to read up on what infallibility is.
In a way, the Pope speaks from the Chair of St. Peter every time he says the NO, or permits the NO to be said by his bishops and priests. The NO certainly has recent Popes' approbation. Are you suggesting the Mass isn't a matter of faith? The Mass is unquestionably a matter of faith, not just discipline. Popes are protected in matters of Faith and Morals--infallibly. Since the Mass is a matter of Faith, does it not follow they Popes were protected from making the Mass defunct? Either Popes have erred in this matter of Faith by providing a Mass that isn't a Mass, and the NO does not confect the Sacrament. Or, the NO is valid, teaches the bare minimum basics of faith and actually does confect the Sacrament, because the Church protected the sheep as far as was possible, and Christ lovingly feeds them His Flesh as promised. No one here on CI doubts that the NO is not what the TLM is, but in order to protect the veracity of the Church, should we doubt what the Church did under the authority of Popes? Should we depart from the Church's authority because they permitted the NO? Or should we submit as Christ did (in all things but sin), fight the modernism within, stay with the TLM, yet refuse to give up what belongs to us--millions of fellow Catholics! It seems to me Trads are far too willing to count as lost the NOs by saying NOs are not Catholic. (Ok, many are not...but not all). Those who insist NOs are not Catholic sounds to me like people who are setting up their own Church separate from the authorities to which they know they are bound. I keep getting faced with these two options: either the Popes erred promoting a false Mass and lost 95% of Catholics back in 1970, or authorities (in spite of themselves) were protected from going too far so that loyal stragglers, weak minded and the uninformed might still be fed by Christ until they wake up. The latter makes more sense to me.