The consideration of burning WG's redshirt was if Harris was done. Now that he's not, I'd be hard pressed to believe they burn it now.
To answer the redshirt questions, it's my understanding that you aren't really given a redshirt until after the season, to remain eligible for a normal redshirt, one (WG) would have not played ANY downs this season. WG being on the field for 1 single snap negates his eligibility for a redshirt, thus why they call it burning the redshirt.
You can, however, still earn a medical redshirt, however you can't have played more than 30% of the snaps on the season and must have had a season ending injury. I've heard people say medical redshirts aren't technically given until the end of the original 4 year tenure, but I'm not sure on that.
If I had to venture a guess at this weeks QB depth chart it would be:
Driskel starting, Mornhinweg as 2nd string with Harris technically being third with the coaches having no plans to play him, but should the unthinkable happen and Driskel and Mornhinweg get injuried (long shot), I'd have to think Harris would get put in over burning WG's redshirt.