Koons raise was him deducing that he didn't have the best hand. However, given Kenney's size (I think he used a 1/4 or 1/3 size), koon likely thought that he had a weaker one pair type hand. Given the odd multiway dynamics (one player all in, small side pot) and given that it's pretty hard to have a bluff there koon opted to turn his hand into a bluff to out pressure on Kenney's perceived range.