I have played and refereed the game and believe it is a knock on. If you catch a high ball and after having had control fumble it into an opposition player it is a knock on, not so different in this instance. Yes he dropped the ball toward his foot with the intention of kicking it but prior to the ball hitting his foot it has hit another player who didn't play at the ball thus meaning he lost control prior to completing his intended kick and knocking the ball on.
Regardless of your opinion it doesn't matter, the game is long over, the result is in the books and it had no relevance on the final outcome.