Perhaps this question has already been answered - in one way or another. If not then surely this question and other questions such as Authority of Church Writings & Councils , could well use a Garrigou-Lagrange or St. Thomas Aquinas type of workmanship. This effort is meant to simply touch on the subject and hopefully prompt discussion.
The overall principle (to the question posed) seems to be that : 'One who has authority over the matter or entity (here we treat a council), has authority to accept or reject the entity - except when a higher authority (the Holy Spirit) takes precedence or is the actual agent behind the entity, making THE ONE WHO HAS AUTHORTY actually a sub-agent or secondary authority'.
There seems to be little doubt that should a pastor call a parish council together to decide certain matters within the parish, the pastor is not bound to abide by the decisions of the council. The prudence of doing so or not doing so is not the question - at least in the absolute sense.
There seems likewise to be little doubt that should the bishop or archbishop of the diocese call together in council some or all the priests of the diocese, so to decide matters like altar girls or communion in the hand, within this diocese, that the bishop or archbishop is not bound by these decisions.
A general or universal council can be called only by the one having universal authority, namely the pope. The pope is free to accept or reject the council's decisions - is he not. The reality that a pope is pre-decided in this matter, it seems, does not change the question of his freedom. (admittedly the teaching of Collegiality seems to confuse the issue - however, it can be argued, down the stretch, that this teaching in Vatican II caries no weight).
Anyway let us simply say :
1. The pope is free to call or not call a council. A wise or prudent pope, especially after the Church became large and complex, would seek the advise and thinking of the cardinals and bishops, on this question of whether or not to call a council.
2. A council serves as an advisory body for the pope. When a council shows that it has performed with great prudence, knowledge and much careful pondering and calling upon the full wisdom of the Church historically, and the guidance of the Holy Spirit during the council proceedings, then the pope should be quick to abide by these decisions. Still the pope is free to accept or reject the decisions, of the council.
3. A pastoral council remains as an advisory council to the pope, and to the Church after the pope approves its decisions. The point is that a pastoral council does not formally bring in the higher authority (the Holy Spirit). We well know that 'solemn pronouncements or defintions which bind every Catholic' are irreversible. Obviously a pastoral council does not fit this mold.
4. Thus there exists no reason to put such a council outside the authority of a pope to change or condemn should sufficient evidence exist to prove this radical move advisable for the good of the Church.