Using private revelation to prove or disprove a point of doctrine or dogmatic truth is not only stupid but also shows how weak the argument is. When opposing sedevacantism or the recognize-and-resist doctrine, its just best to refer to doctrinal statements, papal bulls, the church fathers, theology manuals, etc.
Private revelations should always be taken with a grain of salt, even those that have been met with approval by The Church. However, at the end of the day, private revelations are not binding on the faithful