This one may help create clarity. if he gets off, all about the outcome. If he gets one week, then it is about the action, any hitting of the head. Then you layer on more weeks if arm pinned, more excessive force. One exception will be if tackler worked to reduce the impact and player outcome ok.
Still, is the easiest solution is that if player is tied up umpire blows the whistle earlier. We saw a case where a Saint player was tackling, didn't want to take him to ground. eventually Brisbane player broke tackle and disposed of the ball. Commentators suggested classic example where tackler next time may take to ground otherwise he looks weak to have tackle broken. If ump just blew whistle it makes it a safer decision and most time player doesn't break tackle.
I sometimes umpire amateurs and once player is wrapped upon and I just blow whistle for this reason. Less protection for players at that level (cameras etc) so need to reduce risky actions as much as possible.