Covered by Law 10 – Foul Play
Definition:
“Foul play is anything a player does within the playing enclosure that is against the letter and spirit of the Laws of the Game. It includes obstruction, unfair play, repeated infringements, dangerous play and misconduct which is prejudicial to the Game.”
Law 10.2 deals with Unfair Play and includes the provision:
“A player who prevents a try being scored through foul play, must either be cautioned and temporarily suspended or sent off.”
Law 10.2 (c)
“A player must not intentionally knock, place, push or throw the ball with his arm or hand into touch, touch-in-goal, or over the dead ball line.”
“A penalty try must be awarded if the offence prevents a try that would probably otherwise have been scored.”
My bolding and underlining in each of these.
Working backwards - the penalty try must be based on the offence, not whether the player was there or not.
It is an offence to intentionally knock the ball over the dead ball line.
If a penalty try is awarded due to unfair play, the player must be temporarily suspended (yellow card). It's not a discretionary matter for the referee to decide on as to whether to issue a yellow card or not.
The issues in this instance are therefore was it intentional? And would the try have been scored but for the offence?
Could argue either way on being intentional or not - he may have been trying to ground the ball but got it all wrong.
Would the try probably have been scored but for the offence? Got to be doubt about that - the offence wasn't going shoulder to shoulder - it was tapping the ball away - at the time that occurred the ball was still in the air and who's to know where it would have bounced when it hit the ground.
I think they got it wrong on both intentional and whether the try would probably have been scored. But having made the decision to award a penalty try they got the yellow card decision correct.