There was a time when I thought rugby league was a simple game.Sorry The Who, not super clear so here is GA's quote.
GA said this:
“Regardless of any infringement that might take place by the defender – other than foul play – it’s irrelevant because the ball hasn’t been brought back into play and the referee can’t extend the play for a technical infringement to award a penalty."
I think it was the fact that time had run out and the tackled player still had the ball, hadn't gotten up, hadn't played the ball, so the ball was not in play. In this case the ref can't rule on any technical infringements as time has expired. The exception is for foul play.
I'm guessing that if STG (and for example) said to the ref... 'hey, the raiders guy pushed me over as I was trying to get up to play the ball!'
The ref would answer 'maybe, but he did that after time expired, so there's nothing we can do.'
It's probably better explained in the link, but it seems we're talking about split second determinations here.