I screwed up in my last post — now deleted. I am totally distracted, beside myself, about 8 years under Romney. Rushing, which is another reason for the faux pas, to attend a farewell meeting for the always neat Dr. Mrs. Jill Biden later today.
The eligibility for conclave attendance is calculated as of the day before the sede vacante. Darien N. Clark put me right. My fault. It was in the Paul VI (#264) constitution that the 80-year cut-off was calculated as of the day of the conclave.
So there is a 14 day window of uncertainty. If the pope was not willing to risk that 2 week window, then there must be a reason.