I don't know the first thing about George Quarles, but just from reading here and looking at his resume, here's why I'd take him (assuming his scheme would fit the current personnel Butch has been recruiting).
He's a winner. He's developed habits, consistency, schemes, discipline, effort and work ethic in players consecutively for a long time now. This can translate to college easily. Play calling is just a part of the job, getting players to execute those plays is probably just as important. A great play call ran poorly is not as a good as a poor play call executed perfectly. I would have no problem hiring him directly into the OC position.
Again, not knowing him at all, here's why I think he would accept the OC position if offered. He's a winner, he's proven that. Winner's are constantly looking for a new challenge. Calling plays in the SEC would be a huge challenge.
Lastly, I've read some comments about job security. With his resume, it doesn't matter if he coaches a year and Tennessee averages 35 yards of offense per game, ANY high school in the country would hire him. Including Maryville.