I agree that it's all original code and art, I would even say that he's well within his right to post his clone since there doesn't seem to be any copyright-able IP he could be infringing on.

But I wholly disagree with the notion that "if the game was copied that quickly there wasn't much substance there to begin with". There are limitless examples of world changing inventions that were trivial to build, but no one had thought to do it, and the same goes for art. The difficulty of making something isn't what makes it genius, in fact it's usually the simplicity of a genius idea that makes people go "damn, why didn't I think of that, it's so genius!"

It sounds like this guy accomplished little more than burning the few bridges he had, and dragging his own name through the mud. Just...not a smart move.