I dunno. I was going to say that It does when little minds think that it should, and that I especially liked the fact they cant actually find a rule that is violated.
But then I realized that I havent actually seen your sons delivery, just the other young man in the link above. So hey they have seen it and I havent so their view is at least informed whereas mine is conjectural. If you think it is the wrong decision appeal if possible, otherwise move on and adjust the motion, Afterall its just another judgement call, really. How about if he keeps the leap just doesnt let the foot touch down again?
ANy chance of you posting a clip or a link showing the motion in question?
Say Piaa does it actually say in the rule book that you cant "replant" the foot? Even the foot draggers usually rotate the foot up and around eventually.