Once again I disagree. Here is why. Technically he would be the second string QB at the start of the season IMHO. The only reason he wouldn't be the starter is because he has to sit out 6 games. Now mind you this is of course that he is welcomed back on the team by Coach Mac and the team. Therefore the only thing that he would need for him to take the starting role the second half of the season is a low production rate by the starter (LDR or Applebee). The other two QBs would be red shirted for sure. If he was to be welcomed back so he would only have to beat one of the other two for the back up role. What we don't know is how quick LDR and Applebee will grasp the system, and what we do know that WG knows a lot about the system. Yeah I was a huge WG pumper and thought he was the future, so I might lean a little towards him being the second half starter if he proves his worth through the coaching staff and the team.
No coach in the world would do that unless they want to lose. By definition a guy can't be QB2 if he can't come in when QB1 goes down. As a coach in a violent sport you therefore have to prepare a backup for your starter unless you are insane and want to get fired (or have no backup like UF after Grier was suspended). As such, all the meaningful practice reps would have to go to those who are eligible to play - period. NCAA rules also limit practice time to such a degree that there would be no extra time available to develop a guy in the background either because game planning in the modern era is also very time consuming especially in the SEC. Given those constraints, how would Grier have a chance to get ready to take over week 8 (which happens to be Georgia)?
You seem to think that just because a guy has some skills at a position it makes him capable of being effective on the field without proper preparation. That just isn't true especially at the QB position. Why do you think coaches stress practice performance so heavily? If you plan to have any kind of passing game in the SEC you have to be able to make quick reads and at times throw receivers open. To do that you have to have developed timing with the offense and have committed to memory the basic offensive philosophies including the tendencies of your skill players to such a degree that you don't have to think about them. That's what it means to have the game slow down. On top of that you also have to be able to add in weekly game plans around the other team's defenses including adjustments for the tendencies of their most impactful skill players. The unavoidable lack of preparation would therefore set him up for failure rather than success if he was asked to start playing so late in the season.
In all honesty, it really wouldn't be fair to Grier to put him into that position. Even Peyton Manning or Tom Brady at their college level of development wouldn't have been able to successfully step in under those conditions. Maybe if Grier was an athletic freak like a Cam Newton he'd have a chance to pull it off to some degree because at the college level Cam was able to use his size and sheer will power to ad lib his way around any game planning deficits. Grier hasn't got those types of tools so he would be at a severe disadvantage especially against any SEC defense in mid season form.
As much as I was a fan and excited about his future before the suspension, I've come to recognize that his decision to transfer was really the best situation for all involved. I do hope he finds somewhere to play that can give him an opportunity to redeem himself and any future he may want in football before his eligibility is gone. That just won't be and shouldn't be at UF.