If you haven't used a redshirt year already (Keeton hasn't) and fit the criteria, that's pretty automatic, and it's granted by your conference, not the NCAA.
If you lose *more than one* season to injury it's necessary to appeal to the NCAA for an extension of your original 5-year window (you are supposed to have four seasons in five years available, and a non-injury redshirt year counts), but that doesn't apply to Keeton. He's got another year left in his window, what he lacks is another year of eligibility. A medical hardship would give him that.
This isn't to say that Keeton *will* take a medical hardship year, only that if he sought one there'd be no reason to think he couldn't get it.