Besides, it is not the case of, “The Pope says celebrate the extraordinary rite” and, “the bishop says don’t celebrate the extraordinary rite.” The case is: “The Pope gives permission to celebrate the extraordinary rite,” and, “the bishop prohibits its celebration.”
In this case, the priest cannot possibly be disobedient by not celebrating it, because he is not under obedience to celebrate it.
I agree with ASimpleSinner-- obedience is a virtue, and even the greatest saints-- St. John of the Cross, for one-- had to undergo much adversity in order to do the will of God. Going through the proper channels shows a real respect for the Church structure-- and that is a good thing. The bishop is still the ordinary, and the priest would owe obedience to him. Of course, the bishop has overstepped his bounds here, but that is why the Pope allowed appeal to Ecclesia Dei-- so that these problems could be resolved without anarchy, but in their due process.