Because here is what you can’t do. You can’t put Tim Tebow out on the field and ask him to play at anything less than full speed. You can’t ask him to finesse this situation. That is not his nature. Tebow’s personality and competitive drive will not allow him to do that.And that makes playing him very uncertain.
If Tebow is on the field he can’t hold anything back. If he has to hold anything back, then Tim Tebow should be in street clothes and the team needs to rally behind John Brantley.
The team can win with John Brantley, even if they don't rally behind him (and there are no reasons they wouldn't/shouldn't).
If there is ANY doubt—no matter how slight—about Tim Tebow’s condition then he should not play.
I still think that Tebow will dress. Brantley will start. As long as the Gators are ahead or in the game with existing personnel (read: Brantley), Tebow won't play -- because he wouldn't NEED to play to win the game.
If Brantley is absolutely horrible -- defined more by turnovers (fumbles and INTs) than simply missed/poor passes -- but the Gators are still in it, I could see Meyer playing Tebow.
But Brantley isn't going to be horrible - mainly because, barring dumb turnovers, the system is built to inoculate him from being horrible. Mediocre? Maybe. But definitely GOOD ENOUGH.
And Brantley being "good enough" is enough for a loaded Florida team to beat LSU in Baton Rouge.