Agree, but I wouldn't be opposed to giving one a try this week to see. Unless, that is, the coaches just have no faith in the other 2. And I suspect that's the case. Before the season started everybody here was saying both backups were so much worse than JG that if he got hurt we were screwed, and now one of them is supposed to save the team. If they're that bad it doesn't change just because of JG.
I trust the coaches, who know on each play what the QB was supposed to do and who messed up, who see every minute of practice, who get to looked into the eyes of the QBs, who talk to them, who know what each has to offer, and whose jobs are on the line.