This response is pretty silly from both the defensive and offensive perspectives. Why create more uncertainty over your strength (defense) by shuffling the cards when you know what you have works?
On the offensive side, you're more likely to get a good offensive mind if you put him in at head coach. Why? Because teams can't block coordinators from moving up to head coaches. They can block position coaches from moving up into coordinator roles, and the expert ones do all the time.
If the goal is to keep what you have going defensively, and improve on the offense, then it makes no sense to promote Horton, because that leads to possible backsliding defensively without having the pick of the litter of offensive assistant coaches to work with.
But does it work? You wrote last year the Defensive improvement may be overrated because of the quality of offenses they faced in 2011 and this year the defense regressed once the real refs came back especially against the run.
But with the QB situation who knows. The NFL has come to a point where if your team doesn't have a top QB your team exists just so the top teams have someone to play.