It's the 'in' sign in Tennis as well and Volleyball is very similar. It's often hard to understand someone in a noisy surrounding, that's why we often use hand gestures to clarify our meaning. I dont know what mental gymnastics you performed to come up with the idea of pointing to clarify that it was out. I've seen coaches indicate that a shuttle was in with the usual line judge gesture (if a bit more casual), and even we have done it at times when a team mate is unsure about a line call (we don't have line judges at all, btw, still use the hand sign). Anyway, while it's possible that the coach said sth else (maybe along the lines of 'you were there, play it' or whatever), I'm sure he did not call the shuttle out with that gesture. I'm also speculating that he told LD the shot was in, as coaches sometimes do when the player starts deluding themselves that their judgement was sound and that it's the officials fault. Whatever. He had a diva moment, we'll never know if the shot was in or out, let's move on. As long as he doesn't repeatedly pull that kinda stuff most will probably forget it happened, it wasn't that big a deal.