Correction of typos in the penultimate paragraph:

In short, though the study does make some good points, I would say it is far from conclusive, and reads more like an apology for the liturgical movement, highly compartmentalized to a small span of time in Church history when by the acknowledgement of all traditional liturgists (including those of the SSPX), the movement had long since jumped the rails of Catholic liturgical principles.

Hello Ermylaw-

The SSPX officially teaches in its Liturgy I class that the liturgical movement was no longer operating on Catholic principles no later than 1920.  

Consequently, I believe one ought not confound the legitimate motives and measures undertaken by Don Gueranger and St. Pius X with the modernist contingent which hijacked that movement in the immediate aftermath of St. Pius’s Death.

As regards whether or not the novel introduction of these new Mass postures is indicative of an SSPX sliding into modernism, I would opine that viewing this change of praxis in isolation of all the other changes implemented by the SSPX in pursuit of an accord with modernist Rome is not a sound methodology:

When one views this liturgical change in praxis within the context of both Rome’s stated intention to “enrich” the old Mass, and it’s desire to “reform the reform” to something very close to the 1965 Missal (and further: when one notices how these liturgical changes in the SSPX traject in that direction, and additionally, with the greater ralliement and incremental regularization of the SSPX in view, one would be foolish not to explore the possibility of a connection (a connection I believe the timing, context, and specific nature of the changes in praxis themselves all serve to corroborate).

I understand others may see facts differently: 

“Whatever is received is received according to the mode of the receiver.”

Some into on Fr. Fred McManus.  He was a destroyer.


https://en.wikipedia.org/wiki/Frederick_R._McManus

https://www.lib.cua.edu/wordpress/newsevents/6906/#more-6906

https://www.nytimes.com/2005/12/04/us/msgr-frederick-mcmanus-82-expert-in-catholic-canon-law-dies.html

Associations and ecuмenism
Msgr. McManus served as president of the Liturgical Conference from 1959–62 and 1964-65. He was key in establishing the Federation of Diocesan Commissions (FDLC) in 1968. He was a member of the International Commission on English in the Liturgy (ICEL) from its inception in 1963 throughout decades of translation. He helped promote dialogue between the Roman Catholic and Orthodox Churches. He consulted for the Secretariat for Promoting Christian Unity, was a member of the Catholic-Orthodox Bilateral Commission and served on the International Joint Commission for Catholic-Orthodox Theological Dialogue.

I am not at all knowledgeable about the "liturgical movement."  But is it absolutely necessary that the average Catholic like myself should be?  I leave that to others.  That the Church, though, should have abandoned Catholic liturgical principles by 1920, is a bit of a shock, even to someone like myself who is not overly interested in the subject.
Of more interest to me is the identity of X.  Why? Because knowing who he is and something of his background might influence some of us, anyway, to evaluate more objectively the things that he writes, and his basic Catholic orientation.
But X might offer a clue to his past here.  What is taught in an SSPX Liturgy 1 class is probably not common knowledge to most of the sspx rank and file, cerainly not to me.  It's reasonable, now, to speculate that he may have been an sspx seminarian, or even an sspx priest no longer attached to the organization.  In any case, he might have used a user name like 'xseminarian,' or 'xsocietypriest'  But no, he chooses to double down on anonymity with the simple letter "X."
I'll stay tuned.

Dear Mr. Hollingsworth-

In 2-3 months time, you will know my identity, as well as my reasons for my (then) former anonymity.

Patience.

Long story short, the thinking is probably similar to the situation with altar servers: Ideally, only a seminarian who has received the first 4 Minor Orders (Porter, Lector, Exorcist, Acolyte) has a right to serve Mass. But since most chapels don't have seminarians available, boys in cassock take the job.

Yes, I believe that's exactly what the thinking is.  But it just seems this crosses a line.  Now, most Traditional Catholics object to the Novus Ordo practice of doling out these liturgical functions to lay people, such as having Lay Lectors.  So is seems that this crosses a new line.  But that's an emotional reaction, and it's important to understand where said line is ... based on principles.

Here are the Catholic principles.

Liturgical Prayer, properly speaking, is the public prayer of the Church, and so in Liturgical Prayer it is the CHURCH praying and not just individuals.  So, the Mass, Sacramental Rites, non-Sacramental Rites (such as which appear in the Rituale Romanum), and Divine Office are Liturgical Prayers.  Not that someone might not be able to pray these privately out of devotion, but when done privately they are not Liturgical in nature.

Consequently, Liturgical Prayer requires someone in a capacity to actually represent the Church.  So, for instance, women cannot exercise Liturgical functions, properly speaking, because they cannot serve in the capacity of "heads" to represent the entire Church body.
But, what's more, no mere layman can represent the Church and pray on behalf of the Church.  I'll go on in a subsequent post.

Ladislas, when I was at the monastery I recall that the new holy week rubrically kind of made an unfortunate distinction between the Gospel and the passion, this was I think further blurred by the 62 rubrics which treated the passion as a liturgical act and not a Gospel. Bizzare. The priests always read the passion but I recall that SSPX priests because of the rubrics allowed laymen in cassock to read the synogoga part. Never experienced it until I went to mass in a southern state though

I think Matthew might be scratching his head over this one.  He knows me;and he and other older members of the forum should know me from the past.  It is not that I have ever hidden my identity.  It has been revealed several times over in the past.  Matthew and others can probably verify that.

Matthew might know you but I don't.  How many others do?  Why does it matter if I know you, Matthew does, or not?  Why does it matter if we know who X is or not?  Everything X has posted has been self-evident, but important facts.