It’s the point three that matters here. Though I believe the verbiage in the rule is “immediately behind” or some such? So if the face were more vertical such that “immediately behind and below” fell in the bunker should the reference point have moved?
It seems any controversy is rooted there. Which. The evidence is gone was the ball is removed from the condition alas.
The removal of the ball is irrelevant. They know where the ball was. Its location was marked. Removing it allowed them to verify it was embedded.
The verbiage is "right behind" in the rule, and "not immediately behind" in the Clarification (16.3b/1).
Reference Point: The spot in the general area right behind where the ball is embedded
16.3b/1 – Taking Embedded Ball Relief When Spot Immediately Behind Ball is Not In General Area
Again… the referee in this case didn't think that the reference point could be in "thin air" and it also would have been in the bunker, and didn't think about going "below" the ball to establish the reference point.
I doubt many other people who know the rules even as well as this particular referee did would have, either.