Because the rule is you have to be near on 100% certain to score the try, he was noway near certain to score that. Ball was doing the dirty bounce. Penalty and send off for mine.
But then again it's the nrl, so role the dice. Nobody has any idea, most notably the refs.
You are saying the same thing as the commentators, but you all seem to think it is something it is not.
nowhere in the rule does it mention being 'near on 100% certain'.
it does mention defenders impending a player through foul play from probably (in the refs interpretation) scoring a try.