Your argument doesn't exactly work --
Let me apply it to something else:
Certain men (divers, etc.) can hold their breath for 10 minutes at a time. So why not 100 minutes? Why not 1000?
We've established that man doesn't need to constantly be breathing, so this seems to give credence to the theory that man can go without breathing for days.
I don't think this analogy is apropos to the papacy.
When one holds his breath, he, oyster divers for example, can work very hard and do all those things which he ought and must do. Additionally, this only applies, as you point out, to "certain men"; it is not universal.
When the pope dies, i.e.,
sede vacante, the Church is not "holding" her breath as there are things which the Church cannot do: She cannot confirm a General Council; She cannot make new laws; She cannot make
changes which She may and ought to make. There is no head which can do these and other things a living, breathing Church can and ought to do. Furthermore, holding one's breath must be a
conscious decision. I doubt that many people who think the See of Peter to be currently vacant think that Benedict XVI believes himself to be a usurper. Indeed, I doubt that any anti-pope thought of himself as an anti-pope.
A better analogy might be that when the pope dies, the Church sleeps. She is still completely alive, doing all those things which sustain life. She is running, if you will, on autopilot. Though She cannot do those things which takes a conscious head to do, she can indeed continue as long as God sustains her. The essential life remains, i.e., through the Sacraments, but that life remains as it was when it fell asleep though the longer it sleeps it becomes leaner, weaker, less able to defend itself.
This, I think, would be more in line with how those who believe the See of Peter to be vacant would describe the current situation. The Church is suffering from a sleeping sickness or coma. She is sustained by the "feeding tube" of Grace; but she cannot consciously do those things which She can and ought to do other than the most very basic of life sustaining activities. Further, I am sure that those who, themselves, view Benedict XVI as a usurper would agree that Benedict himself does not share that view. The New Church which he heads is consciously doing all those things it desires to do while the Catholic Church unconsciously continues doing those things essential for salvation: Teaching the Faith and providing the Sacraments.
Obviously, this is not a perfect analogy, but it better describes, I think, the universal aspect of the current situation according to the
sede vacante theory.