The weird thing to me is that Hamilton may have indeed been recklessly chucking when Goodman watched him play. But it was one throwaway weekend at a stupid AAU tourney after he had already committed - maybe he was playing with riff-raff and the coach wanted him to shoot a lot, or he was just simply using the tournament to work on some things. Getting good shots off under heavy defensive pressure -fadeaways, quick pullups, etc. - is a skill that requires some practice in game settings.
He played with his HS team just recently in an out of season event and had 17 points and 10 assists, after averaging 7 apg last year. I'll grant you that HS stats can leave a little be desired, and the scorer might be generous, but he would still have to give up the ball to get those numbers.
So in Goodman's world, the one weekend he saw him play at some AAU event defines who he is as a player, and not his body of work in a structured system.