It is from a 1950 article by Msgr. Joseph Fenton (as is clearly stated in the OP), conservative and arch-enemy of Fr. John Courtney-Murray and his theses on religious liberty. He served with Cardinal Ottaviani on the preparatory commission for Vatican II which produced the document on "Religious Tolerance" rejected by the Council. As CatherineSiena posted:
Msgr. Joseph Clifford Fenton was one of the most eminent theologians of 20th Century America. He was trained at the Angelicum in Rome and did his doctoral dissertation under the revered theologian, Father Reginald Garrigou-Lagrange, O.P. From 1944 to 1963, he was editor of the theological journal, the American Ecclesiastical Review. He also defended the doctrine "outside the Church there is no salvation," and upheld the traditional Papal Teaching on the Confessional State.
The fact that you don't know who he is indicates that you have not even read Michael Davies' book on religious liberty - yet you have the audacity to judge the Supreme Pontiff a heretic!
You are correct that the Church cannot err. Your conclusion is that the novus is therefore correct. Wrong. The correct answer is that the novus ordo missae, and those who promulgated it, are in now way part of the true Body of Christ, the Roman Catholic Church - rather they are of satan, as are their works.
You'd do better if you read the article. It has an interesting part which states the proposition "the Church of the city of Rome can fall into error" was condemned as manifest heresy by Pope Sixtus IV. This thesis is exactly the error of Luther:
For many years now, nothing else has overflowed from Rome into the world -- as you are not ignorant -- than the laying waste of goods, of bodies, and of souls, and the worst examples of all the worst things. These things are clearer than the light to all men; and the Church of Rome, formerly the most holy of all churches, has become the most lawless den of thieves, the most shameless of all brothels, the very kingdom of sin, death, and hell; so that not even Antichrist, if he were to come, could devise any addition to its wickedness...
And it is exactly the thesis you hold! But as is pointed out - the Roman Church is indefectible and infallible. This means the diocese of Rome will persevere until the end of time. And this is what proves the error of the sedevacantist heresy - it holds that the local Church of Rome has fallen into error - for as Pius XII points out in Mediator Dei: "let the rule for prayer determine the rule of belief" (§48) - and ceased to be part of "the true Body of Christ, the Roman Catholic Church".
Is there any way to get ahold of old copies of the American Ecclesiastical Review? The individual articles I've read from it are outstanding (including contributions by Ottaviani) and there are few writings you can find these days that are comparable in breadth and scope (the possible exception being John McCarthy and Brian Harrison's work for the Roman Theological Forum).
It may be a worthwhile project for someone to look into what it would take to transfer the material to the Internet. At a time where Catholic Universities have stripped the title "theologian" of any useful meaning, the wisdom of dedicated Catholic theologians of a generation past are welcome and necessary.