Any play time will burn a redshirt. If it happens early in the season (first 30% of the season) than they can get a medical redshirt. Haven't heard about any injuries for Blankenship but I'm sure they can come up with something.
We've had a discussion on this, and can't recall which thread, but I think this is a misconception, unless the rules have changed or I was misinformed. I had a friend that played DI, and played in his first 4 games as a freshman. We went to party one night and he told us that he was going to redshirt after all. He said that as long as it's the first four games and you play a certain % of snaps, you can still get the redshirt.
It's also completely possible that he misunderstood and that the coaches were going to give him a *medical* redshirt after the fact.
Also, I think I've shared this story before, so I apologize to others who might view it as redundant.