Why risk it? Tough spot, what if we are actually in contention for the playoffs? He also won’t have the benefit of OTA’s, timing, etc.... What if the line still needs to hell? At least Fitz is used to it.
So many variables. Any disruption or shortening of camp will affect him.
When our biggest problem is figuring out when to start our highest draft pick at QB, it means we are in really good shape at QB.
This being the case, we don't have to force anything. With a revamped OL, it will take 4 or more games, at the least, to get well coordinated as a group. Why would you want to put your most inexperienced NFL QB behind that line? We would not win as many games and could conceivably "stunt" a rookies NFL growth. You don't need to look very far to see examples of potentially good QB's who's development was hindered early in their career by poor OL play.
We know that Fitz was successful behind last years OL after it gelled. He is likely to be our starter. Rosen may have developed well this last year, but only the coaches know if that is the case or not. If he has developed and it turns out he outplays Fitz in training camp, he could be our starter. All rookie QB's take some time to adjust to the faster pace of NFL play. They also need more time to learn the playbook and be able to implement it. Think of it as a gradual breaking in process. These are solid reasons to limit his QB play for a while. How long that is will depend on two things.
1) How well our starting QB plays, who ever that turns out to be. If they are playing well, we keep them playing. We can rest them after we are well ahead if want to give our rookie QB enough snaps, so that he has a chance to develop some rhythm with the team and start getting some game day experience.
2) How fast our rookie develops during his first year. Lets give this man every chance to be successful as opposed to rushing him out on the field just to satisfy the "Lemming" lust that seems prevalent on this board. If Tua is your guy and you are expecting great things from him, why would you want to rush him onto the field before the coaches feel he is ready?
Hint, there is not a valid answer for this question!