He very well may be best suited to be a coordinator. Many coaches have been. But the thing is, they oftentimes learn that by having multiple cracks at a head coaching gig. Think Wade Phillips, or Norv Turner and Josh McRoberts from the offensive side.
It's possible that the Miami experience soured him on being a head coach, or that he truly is blackballed, or that the ongoing legal proceedings prevent him pursuing a head job at this time. Maybe the general preference for an offensive playcaller as head coach gives front offices enough plausible deniability to overlook him.
But my money is on him getting a head job again some day. I think he's too young and too good not to get another opportunity eventually