For these reasons, I say Bugnini/Pius XII introduced a Novus Ordo of holy Week.

Cute, but it sounds an awful lot like you're saying the Crisis in the Church proper started before Vatican II. That goes against the common opinion of most Traditional Catholics.

Also, POPE Pius XII (accepted even by most Sedevacantists) was not Bugnini. His name was Eugenio Pacelli. Regardless of the Freemasonic pedigree of Bugnini, Pope Pius XII signed off on the changes, so he took responsibility for them. Ergo, you can't push it off on Bugnini. It's Pope Pius XII you have a problem with.

I have a few questions for you though --

Why did +ABL go along with the new Holy Week? Why did he never speak out against the new Holy Week, such that his Society used the new Holy Week exclusively? Was +ABL afraid of censure? A slave to human respect? An imbecile?

If you were transported to late Lent 1960, and had to spend a few weeks there, would you go to Mass on Sunday? There would be no Trad chapels yet -- only your local parish. Would you stay home on Sunday, to protest this evil new "Novus Ordo" Holy Week?

For these reasons, I say Bugnini/Pius XII introduced a Novus Ordo of holy Week.

Sure, that much is clear.  But if the Church created the liturgy of Holy Week (i.e. it's a human creation), then the Church can change it.  Is the Holy Mass on Holy Thursday altered?  No.  And there's no mass on Good Friday/Holy Saturday, so again, the mass isn't changed.  Nothing of Divine origin is changed.  As much as we recognize the changes are modernist, such changes are not an essential change to the essential parts of the liturgy/faith.

Sedes argue from the legal principle of epikeia.  Since there is currently no lawgiver, they suppose that a legitimate lawgiver would have rolled back the changes once realizing that they were transitional to the NOM.

It's making a mountain out of a molehill, imo.  Sure, the changes are modernist but that doesn't mean they're heretical.  And, being that I think Pius XII was valid, I don't feel comfortable disobeying a liturgical law without a better argument. 

Several years ago I read an article, or essay by Rama Coomaraswamy (yes a very controversial figure in tradition) in it he showed a side by side comparison the changes made to Holy Week. At the time I was shocked how much was cut from the original, long and involved ceremonies. Absolutely beautiful content btw, and I have since hoped for the opportunity to attend them as they were done before the changes. 

I did discuss this with someone else after reading it, I forget who, and they suggested that possibly they were streamlining Holy Week due to decreased attendance, and perhaps to get more to come back and attend the ceremonies that were now shortened significantly. 

I wish I could locate that article by Rama but I can’t find it anywhere online as of yet. Rama’s opinions mean nothing if you can see the comparison for yourself. 
I personally don’t judge the pope and his decisions on it, but it is sad to see how much was removed from Holy Week. I hope to see it restored someday during my lifetime. 

from Wikipedia about Pope Pius XII:

Late years of Pope Pius XII

A long illness in late 1954 caused the Pope to consider abdication. Afterwards, changes in his work habit became noticeable. The Pope avoided long ceremonies, canonizations and consistories and displayed hesitancy in personnel matters. He found it increasingly difficult to chastise subordinates and appointees such as his physician, Riccardo Galeazzi-Lisi, who after numerous indiscretions was excluded from Papal service for the last years, but, keeping his title, was able to enter the papal apartments to make photos of the dying Pope, which he sold to French magazines.[262] Pius underwent three courses of cellular rejuvenation treatment administered by Paul Niehans, the most important in 1954 when Pacelli was gravely ill. Side-effects of the treatment included hallucinations, from which the Pope suffered in his last years. "These years were also plagued by horrific nightmares. Pacelli's blood-curdling screams could be heard throughout the papal apartments."
…
With frequent absences from work, Pope Pius XII had come to depend heavily on a few close colleagues, especially his aide Domenico Tardini, his speechwriter Robert Leiber, and his long-serving housekeeper Pascalina Lehnert. 

So he was gravely ill in 1954 and was increasingly "checked out" from that time forward, delegating a lot of his duties to others.  That would be the perfect time for a Modernist to swoop in and roll out the changes.

Why did +ABL go along with the new Holy Week? Why did he never speak out against the new Holy Week, such that his Society used the new Holy Week exclusively? Was +ABL afraid of censure? A slave to human respect? An imbecile?

Not that this helps much but I did ask Fr Hewko this question years ago after reading about the significant changes to Holy Week, and his response was that ABL had to compromise on some things at the time and Holy Week changes were not a hill he was meant to die on. 
I cannot say this as a direct quote from Fr because it was approx 3 years ago, but it is what I took from our conversation about it at the time.  

No, I think you're the only one here who considers the 1955 Rites a "molehill".

Regardless, the premise is a sedevacantist one, that the See is currently unoccupied and there is no lawgiver.  Consequently, they're operating on what they think a lawgiver WOULD do under the circuмstances.

No, Pax isn’t the only one.  See Matthew’s ignorant/idiotic post at the top of the page.

He must have flunked their liturgy class we were in together.

the See is currently unoccupied and there is no lawgiver.  Consequently, they're operating on what they think a lawgiver WOULD do under the circuмstances.

To me, that logic only applies to situations which happen AFTER the last legitimate lawgiver died.  Whatever.  ...But your post about Pius XII being sick and having to delegate many things makes a lot of sense.  Modernists would have taken advantage of that situation to the nth degree!