apples and oranges
1) Patriarch is appointed by the Pope and can be removed by the Pope, whereas Popes receive their authority from God and cannot be removed formally by the Church. So in the case of a Patriarch, there's a higher authority to which one can appeal.
None of that matters. The council decreed that no one is to separate from their Patriarch until a synod has investigated the matter and rendered a judgment. It is absurd to say that applies to all the Patriarchs except the Patriarch of the West, simply because the Pope "cannot be removed formally by the Church." If he or any other member of the hierarchy remains in visibly possession of their office, and no judgment has been rendered by the Church, all their acts of jurisdiction remain valid, and their subjects are bound to remain in communion with him.
2) Patriarchs do not have infallible Magisterium and Universal Discipline.
Another statement that has nothing to do with what the council decreed. And I doubt you even know what disciplinary infallibility means.
3) This is referring to a simple crime (vs. loss of membership in the Church). ...
No it's not. Read the history leading up to the council. One of the reasons they were separating from their Patriarch is because he was accused of heresy - a "major crime" that separates a person from the Church.
Loss of membership has different implications (vs. an ordinary crime) in that it renders the one who lost membership incapable of formally exercising the office.
Yet another failed attempt to justify rejecting what the council decreed.
There are differing opinions about what is required to be a true vs. apparent member of the Church. Some believe the internal virtue of faith is necessary for
true membership, and some believe mere external union with the Church suffices. But both opinions agree that external union suffices for a bishop to "formally exercise" their office (which is a term you won't find used before by any pre-Vatican II theologian or canonist), since visible possession of the office and common error suffice for all their acts of jurisdiction to remain valid.