I personally hold that a bishop appointed by a material pope can formally exercise office so long as he does not have any impediments to it (i.e. is not a heretic or excommunicate).
Yet you attack me. Vatican 2, ecuмenism, religious liberty, defense of the new mass, collegiality, and loose NFP is an impediment. I mean, the NO bishops universally are opposed to +lefebvre and the old sspx. That is a clear sign of a heretical impediment in my opinion. That is why I generally say remove the NO bishops(the pope remains) from the una cuм, and doubt their legitimacy. I simply have enough conviction to put into practice.