The tribunal decide it was medium impact, not low impact
"The Tribunal panel disagreed with that submission.
The panel said Spargo's one pinned arm, the rotation in the tackle and a "forceful, driving action" created enough danger to warrant the higher grading.
"Whilst Spargo was not injured in the incident, we consider that there was real potential to cause injury," Enbom said."
Seems enormously subjective to me. We do at least have some insight into how they think. To my mind it is a "legal interpretation that may not be intuitively obvious to those who are used to using a non legal classification system." I am guessing that player's must all be aware that the onus is now on them to avoid preventable head injuries when bumping or tackling.