This poor kid and his doting father have been made international fools and are today the laughing stock of the world! He did not prove anything. The 'impossibility' lies in provided explicit solutions to the position of the projectile as functions of time as a finite closed form expression. That's why they compute this numerically. So sad that he will be laughed at for the rest of his life on this planet. His father also looks like a fool which is really, really sad.