TL;DR The referees got it so wrong - because Rules
This was 100% the WRONG call. The
Rugby League Laws of the Game, and the
2016 NRL Laws and Interpretations do not (in any way) indicate that this should have been a penalty try.
Let's look at the relevant rules:
Section 6. Rule 3(d) said:
Penalty Try - 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. A penalty try is awarded between the goal posts irrespective of where the offence occurred.
Note that unfair play is not defined anywhere in the
Laws of the Game, nor the
NRL Laws and Interpretations.
Section 15. Rule 1(a) said:
Definition of misconduct - A player is guilty of misconduct if he trips, kicks or strikes another player
Note that it is only illegal to kick another player.
The 'Billy Slater' rule said:
There is no Billy Slater rule. Billy Slater was penalised, and charged under the existing misconduct rule - because he was kicking another player, while attempting to dislodge the ball with his feet.
Due to the frequency that Billy Slater and other fullbacks began sliding in with their feet, the interpretation of the misconduct rule became:
Referee Interpretation said:
a player cannot attempt to dislodge the ball with his feet while trying to stop a try being scored.
However this interpretation is missing a key qualifier, that is:
Correct Referee Interpretation said:
a player cannot kick another player, while attempting to dislodge the ball with his feet while trying to stop a try being scored
The referees have forgotten the context surrounding their interpretation. All they remember is the type of action that is outlawed, without thinking about the rules, and why the interpretation came about. They have jumped from their incorrect interpretation (cannot dislodge a ball with your foot) in a sliding motion like Billy Slater popularised, to saying that you cannot kick dislodge the ball with your foot full-stop.
They can't even use the contrary conduct rule to get the penalty try decision:
Section 15. Rule 1(i) said:
Definition of misconduct - A player is guilty of misconduct if he behaves in any way contrary to the true spirit of the game
Considering that you are allowed to:
- Steal the ball if the player is attempting to score a try (Section 11. Note for Rule 9)
- Kick the ball in any direction during play (Section 5. Rule 3)
I'm not sure how this action could possibly be contrary conduct. Stealing the ball is not defined in the
Laws of the Game, and thus is allowed with both hands and feet - so long as the stealing action does not result in the player striking or kicking the other player.
TL;DR The referees got it so wrong - because Rules