Please explain me the teaching of the Church on the subject of validity of papal excommunications.
I’ve met one priest who holds that popes can only excommunicate members of the Church for real and grave reasons, and any excommunications for absurd, political, not genuine, or otherwise non-substantiative reasons is null and invalid, even if officially declared by the Pope.
Is such a statement correct? Are there any official documents on the subject?
Or is it true that the Pope can legitimately and effectively excommunicate any member of the Church for whatever reason?
In such a case, is the following excommunication valid and is anyone who mentions in a word or thought Pope Alexander VI in danger of excommunication, or maybe even has already incurred excommunication latae sententiae?
Because, according to Wikipedia, Pope Julius II said:
I will not live in the same rooms as the Borgias lived. He [Alexander VI] desecrated the Holy Church as none before. He usurped the papal power by the devil's aid, and I forbid under the pain of excommunication anyone to speak or think of Borgia again. His name and memory must be forgotten. It must be crossed out of every document and memorial. His reign must be obliterated. All paintings made of the Borgias or for them must be covered over with black crepe. All the tombs of the Borgias must be opened and their bodies sent back to where they belong—to Spain.