This medical hardship was making me crazy as well but I think I have found the answer in this link:
TD LEE :: Lee Suggs :: Virginia Tech
The problem is that there are two components. The hardship waiver is granted by the conference- not the NCAA - and can be granted at any time.
However, the hardship waiver does not extend the 5 year clock. That can only be granted by the NCAA and can't be requested until the clock is used up.
So Clifford may indeed have his medical waiver, but that does not guarantee the sixth year.
The only reason the medical waiver has value without the sixth year is that it allows a player to play some games before being injured and still use that season as their traditional RS year.