I would rather give Kelly at-least a little preseason action before letting him in a real game for any reason.
I agree that Lynch is bad as hell right now reading defenses, I just have no proof Kelly is any better at that because he hasn't thrown a ball against an opposing NFL defender yet.
For that reason, if I was essentially doing what we did with Tebow and just saying what the hell, just throw the kid in, it would be Lynch and see if he improves.