If he's getting a grip on this stuff at an early age, that's all well and good, but there's no salary for professional urination and no one recognizes being potty-trained as a talent, not after the early years.
Writers could drum up a premise (plot involving alien invasion?) for Tic-Tac-Toe, but it's icing that developers /might/ pay for. You could drum up a well-balanced multi-currency system for Street Fighter (not facetious; the system would improve the game) but it'll never be center-stage or priority.
While I wish the mechanics and foundational designs of many games would consult better minds (gaming at large still hasn't outgrown single-purpose "crafting" hallways that are pointless) there's just no market for something so saturated. The "many games" I speak of? They usually at least collaborate and use what my first line referred to: A sufficient level of general competence that results in adequate mechanics/systems in the game.
A "good idea for a game" is pretty worthless. If you've ever been to a con or kickstarter there's a million dreamers hawking their card game or tabletop of "unique and innovative" design/mechanics.
There's probably a reddit for them. I don't do leddit (or any socnet) but it's a functional place on many boards, I'm sure.