This is not necessarily true, as those who have faced issues with subordinates can tell you, any more than it is true that the priest is valuing altar boys over his bishop. The bishop is the head of every parish and the priest operates in the name of the bishop. It is critical that no priest misunderstand this fact. I agree that this one issue would make a ridiculous reason to remove a priest. However, if could well be indicative of a pattern of lack of obedience, or a pattern of the priest moving a parish in a way the bishop does not want…
By definition, this would not be indicative of a lack of obedience. Aquinas defined the Virtue of Obedience as conforming one’s will to the will of the one who has authority.
The bishop does not have the authority to demand the use of altar girls. Since the bishop lacks that authority, by definition, this cannot be disobedience.
You are 100% correct that the priest operates in the name of the bishop, which is precisely WHY a pastor cannot mandate that an associate pastor (or visiting priest) make use of altar boys. The pastor operates in the name of the bishop, and the bishop himself cannot make such a mandate. And any attempt by a bishop to do so, is by definition, a disobedient act. As the bishop himself has not conformed HIS will to the will of the one with authority.
I actually know of a specific, real case. A man who was about to be ordained to the priesthood was invited by the pastor of my then parish to say a Mass of Thanksgiving. The seminarian in question had done his parish internship there and was well known in the parish.
The seminarian invited 4 boys with whom he had worked ( my son being among them) to serve at the Thanksgiving Mass. The pastor heard of this, and mandated that at least one girl be included. This seminarian did not want to revoke the invitations, and was unsure of what to do.
Fortunately for him, a Dominican priest was living the rectory of that parish and had heard of the incident. He, (being a Canon Lawyer) was familiar with the Vatican ruling and attempted to dissuade the pastor from the mandate. The pastor still refused. So the Dominican informed the Archbishop of this clear disobedience.
The Archbishop ( Cardinal Maida) informed the pastor that he had no right to give that instruction and to cease attempting to do so. The pastor had the right to refuse the Mass of Thanksgiving at the parish, but if he did so, he was to inform the faithful as to his reasons for cancelling the Mass.
The Mass was said, the altar boys served.
FYI, that was over a decade ago. The seminarian is now a pastor himself (and yes, uses only boys in altar service at his parish)