I'm guessing he ran it on Quora to see if it would gain any traction, and since it did, either submitted it to Gamasutra or was asked by them to publish it ther

I'm guessing he ran it on Quora to see if it would gain any traction, and since it did, either submitted it to Gamasutra or was asked by them to publish it there. Since it's his answer, he can reproduce it anywhere he wants without crediting Quora as a source (since he's the source here), though it'd be sweet if he gave Quora a nod :)