Then quote anyone before Vatican II who taught that the intention to undermine the faith will prevent an officeholder from acquiring the authority of the office that he legally holds.
It's a simple application of principle that the Church is both a human AND a Divine institution. Christ gave St Peter the power to "bind and loose", but there are limits to this (i.e. St Peter did not have the authority to create an 8th sacrament.
Canon Law (and many other papal docuмents) refer to excommunications which happen "immediately" (i.e. spiritually) while also allowing the necessary temporal due process of law (i.e. human aspect). Just like sacraments have matter and form, so the papacy (being part of the sacrament of Holy Orders) has a human and divine office.
Further, when we read the revisions to conclave election laws changed by Pope St Pius X and Pius XII, both refer to spiritual penalties being "paused" until the election is over (i.e. human voting), but then *immediately* such (spiritual) penalties are incurred again. In other words, these popes differentiated between the human aspect of the conclave/papacy and the spiritual aspect/authority.
cuм Ex makes the same distinction, but not as clear because it's so old. Both Popes Pius X and XII knew the imminent dangers/confusion which was coming upon the Church; they acted accordingly and made the proper separation between the human/Divine elements in the papal office. Same as did St Bellarmine and those of his time.
This concept is nothing new; but the application of it to an actual pope (i.e. every V2 pope) is unprecedented. When the shoe fits...