I think this is one of those situations that OB.. has posted about, where the Law gets very sketchy due to the proximity of the goal-line.
My questions from observations:
1, does it matter that blue player is in goal? (See feet)
IMO, no, because the Law only refers to the tackle. A tackle (noun not verb) cannot take place in-goal, therefore there can be no gate in-goal. However, in this case, the tackle is in the field of player as is the tackled player, so there is a gate and IMO, arriving players must comply with it (Law 15.6).
2, to me blue player is quite clearly in replay going for the ball, not the player, to save the try.
Makes no difference to me. The player has been tackled and there is a gate. The arriving player (Blue 12) must play the ball from his own side of it. The Laws say he has to approach from the side of the ball or the tackled player closest to his own goal-line, it doesn't say that he has to be between the ball and his goal-line.
3. what is the difference between this, and the common try saving tackle (which I never see penalised) where an arriving player comes in hard from the side to bundle them all into touch?
That situation occurs when the ball carrier has not yet been brought to ground. A ball carrier can be tackled from any direction. The gate only applies once the tackle (noun not verb) begins.
4, Should the fact that his actions are not foul play, but try prevention be taken in to account?
Did Blue 12 commit an offence? YES
Did Blue 12 commit this offence in order to prevent a try being scored? YES
Did Blue 12 commit this offence intentionally? IMO, YES
Therefore it is Foul Play under Law 10.2 (a), the player intentionally infringed and had he not done so, would the White player have scored a try? Probably, so PT must follow.
This all might seem harsh, but IMO its fair enough. I have no sympathy for Blue. This situation, does not arise if Blue defends properly. Blue 12 was out of position and could not get to the tackle in time. Why should the referee remedy his mistake/poor defending by applying the law differently than he would anywhere else on the field?
There may have been a possible remedy for Blue 12
[LAWS]22.4 OTHER WAYS TO SCORE A TRY
(e) Tackled near the goal line. If a player is tackled near to the opponents’ goal line so that
this player can immediately reach out and ground the ball on or over the goal line, a try is
scored.
(f) In this situation,
defending players who are on their feet may legally prevent the try by
pulling the ball from the tackled player’s hands or arms, but must not kick the ball.[/LAWS]
If he had arrived and stayed on his feet to rip the ball, he might have avoided the PT, although I would still argue that he is still not playing the ball from his own side of the tackle. I would like to hear from a higher-up referee like KML1 or Bryan on this one.