What is impressive is to make a whole game and finish it! Even though 50fps scrolling was perfectly possible on the A1000, few games had it - partly due to the state of the art, partly due to 6-month contracts
and partly because many games had more stuff moving about on-screen.
But even if it's probably running on an AGA Amiga with accelerator, there's quite a bit of code and work to do such a thing... enemy handling, collision detection, level editing... and at an early age like 14, not very many have the necessary programming skills.
Sad that he won't release it, if he want to keep it to polish it before a proper release, he could at least release a "preview" - just in case the proper never gets completed