Firstly the parents and the teachers should not be sad of this ,but should happy of his amazing talent.To me, if someone shows special talent in something, they should not be held back.
 some possible solution could be:
Maybe he could sit down with his parents and a school representative and jointly come up with a plan that suits everyone.

 Being able to negotiate a routine that works for both his sports and education will obviously be the best resolution to this problem.

hope my answer helped u alot.. ^-^