You make some good points and I apologize if my language is not perfect. I'm just a layman; I'm not a theologian nor a lawyer. However, let me clarify a few things, concerning your points.
1. When I say "rite" I mean the same thing as "missal". The N.O. is both a new rite and a new missal.
2. When dealing with the modernists, we must change our point of view and look at things differently. We are dealing with revolutionaries who are seeking to destroy. We are at war, in a sense. It is a battle of Faith and a battle of truth. Much like a 5 yr old child, the revolutionaries are always seeking the answer to the question: "What can I get away with?"
3. You said: "but according to the teaching of the Church he is able to modify the existing rites of the sacraments and promulgate new rites. That is what Paul VI attempted to do."
The facts show that Paul VI did NOT attempt to modify the existing rites. He is ABLE TO MODIFY the existing rites, but he did not attempt to do so. He did create a new rite/missal. This is a big difference.
4. You said: "If Paul VI was the Pope, then he could not have been bound by Quo Primum (just as St. Pius X was not bound by it or his revision of the Missal would have been illegal) and he had the power to impose a new rite, even without actually abrogating the old one, but leaving them as parallel rites."
First, Pius X was bound by Quo Primum until he legally revised it, and in his revision, legally pronounced that he was revising it. The point is, Church law works like any other law profession. Law A exists. If you want to change it, you have to say you're going to change it and then follow the proper procedures.
Second, yes, I agree, Paul VI has the power to impose a new rite/missal, which he did. However, he did not bind or permit anyone to use it. He created a new missal and said "Here you go! Look at my new shiny missal. Vatican II said we should have a new one, so I made one. I wish that this missal become law on the first Sunday of Advent."
5. You said: "How could it have no legal standing if it was legally promulgated, as you said before??!"
Being that he did not specifically revise the 1962 missal, nor did he revoke Quo Primum, this means that NO ONE CAN USE IT, legally. And that's the great genius of it! Everyone assumed that if a pope created a new missal, that they had to use it. Everyone assumed that Quo Primum was "old news". Everyone assumed that Quo Primum forbids creating a new missal, but it doesn't.
I'm bad at analogies but here goes one: Imagine you're at your friends house for fishy fry dinner, on a friday. Now, you, being a good catholic and knowing your friend is a good catholic, you both normally do not eat meat on fridays, as is church law. However, once dinner is ready, the host brings out 2 plates for each person sitting at the table. One plate is full of delicious fried fish. On the other plate is a big, juicy fully dressed steak burger. Of course, you are not going to eat the steak burger and you choose fish, but he gave you the option to eat each one.
Was this very catholic of your friend? No. Did it violate Church law? No. Church law doesn't say you can't cook burgers on friday. It doesn't say you can't buy meat on friday. All it says is, you can't EAT meat on friday. Was this a "catholic, moral" thing to do, to tempt you with meat? Obviously, not.
The same with the new mass. Church law/Quo Primum never said a new rite couldn't be created. It never said that a parallel rite couldn't be issued by the pope. All it said was, you can't SAY or ATTEND any rite/missal other than the approved one. The N.O. is an invitation, a temptation to sin. That is the devilish genius behind it.
We are now dealing with the aftermath of it's genius and diabolical mayhem. Those Catholics in the 60s and 70s were FULLY AWARE that they were eating the steak burger. They didn't care. They WANTED the changes. No one twisted their arms. I've talked to plenty of people from that generation. They knew/know what they were/are doing.
And the revolutionaries, much like a 5 yr old, studied the law and knew what it did and didn't say. They offered a temptation, they offered confusion, they offered a new religion and most fell.