It's definitely an in case of emergency break glass scenario.
But, QB1 going down, QB2 looking rough... I've got to think they're thinking really hard about what they can get out of Carney's 4 games (he has 3 more to go to keep his redshirt).
If they think he can help them win, I think they'd want to get him in quickly. There are 7 games left. It'll be pretty dumb to blow his redshirt on 5 games, where one of them was a game he played one snap in. I think you can make the year worth it if he appears on at least 6.
And the bowl game.