The whole Bennyvacantist argument is based on an assertion that is simply false, i.e., that munus and ministerium mean two different things and are mutually exclusive terms. In reality, there is a certain amount of overlap between their meanings, more than enough to debunk any claim that Benny was certainly using the words to refer to two separate things, i.e. the office and the function of the office.
Yeah, there's a false argument that Canon law requires a certain "word" to be used in a resignation simply because it chose one or the other of these terms to describe it. In fact, Canon Law doesn't even require a formal resignation docuмent. Just says that he has to sufficiently make his intentions known. He could simply walk out and say, "Later guys. I'm done with this pope stuff." so that anyone could reasonably conclude that his intention was to quit. In fact, there's a principle that abandonment of an office is tacit resignation. Since Ratziger has not pretended to exercise any papal authority for almost 10 years now, that would suffice for a tacit resignation. If you had one of those corrupt Borgia popes leave the Vatican, go around the world womanizing, and doing none of his papal functions, that too would be enough. Now if it was found out that he resigned under extreme duress, that would be a different story and a stronger argument. Also, the fact that Bergoglio's election was clearly engineered and orchestrated beforehand, that would (by even JP2's prior decree) invalidate the election.
No matter how you slice it though, Bergoglio is no more the pope than I am.
Ratzinger couldn't have made it clearer, using the circuмlocution " in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is."
I don't see how it could be made more explicit.