I get what you're saying but Bryant didn't have to leave Clemson to make the NFL. If he plays very well this season, he improved his chances though. If I were a Clemson fan I wouldn't like it but would understand it. Anyway, the obvious point is Hartman is in a very different position with the ability to play 1/3 of the season, redshirt, and spend two years as an upperclassman starting qb in the ACC for a very good coach in a system he's already proven he can run. I don't think he'll even consider transferring unless Kearns (or someone even younger) beats him out.
If he sat for the last year and 10 games of college career, he'd be very, very lucky to ever get drafted. It would be stunning if anyone would take a flyer on him in the 5th+ Round. If you aren't good enough to play in college, why would an NFL take such a chance at that position?