Definitely has nothing to do with it - you can never be 100% sure a try will be scored, the player could have a heart attack and die!
The rule is that "the referee may award a penalty try if, in his opinion, a try would have been scored but for the unfair play of the defending team."
So it was the video ref's opinion that Carney wouldn't have scored if not for Cronk's ten metres worth of holding back. I can't believe that for one second, Carney was delayed so much, he would definitely have got there first, given in the end Slater only beat him by centimetres. Should have definitely been a penalty try.
That would have meant no sin binning though - in the end, NSW ended up getting more advantage from the sin binning, because they put 14 points on in that time.
It was also a terrible call that Queensland didn't get a line drop-out when Jennings hit the ball out of Tate's grasp with ten to go.
Some shoddy officiating in that game, once again.