The story is his family moved to Alcoa. There are 3 school systems in Blount County: Blount County (Heritage and William Blount), Aloca, and Maryville. If your family moves from one school system to another, per TSSAA rules, you don't have to sit out.
Usually the good players in the county go to Alcoa or Maryville when they start high school (via moving there or supposedly paying tuition, as you can do in those systems), so suffice to say the Heritage coaches were a bit surprised, but hardly stunned.