And top it with the stupid sede-something (akin to Meg's sede-whateverism). If you believe that the See is occupied, then you're a sede-whateverist also, a sedeplenist.
For the record, neither +Lefebvre, nor +Castro de Mayer, nor +Williamson, nor +Tissier are sedeplenists. They have all publicly doubted the legitimacy of the V2 popes, which you cannot do if you consider their legitimacy to be dogmatic fact ... as sedeplenism requires. This is the position I have termed sede-doubtism.