Just to be clear. the moss was detached, therefore it was a loose impediment, and you can not touch loose impediments on your backswing in a hazard (water hazard or bunker)-If the moss were part of the ground( rooted and growing in the bunker) no penalty.
If its growing (grass, ivy, leaves, etc) in either a bunker or a water hazard, you can touch them on your backswing (Note under 13-4 says "At any time, including at address or in the backward movement for the stroke, the player may touch with a club or otherwise ..... any grass, bush, tree or other growing thing")
I applaud her talents, but the great thing about the Rules is that they treat everyone equally and cut no one any slack. Just because she is 16, the Rules do not and should not "extend her a break" (In fact Michelle has illustrated a willingness to push the envelope a little in trying to use the Rules to her advantage).
The Rules do not guarantee you the right to make a full backswing--if the ball is in a bunker where its surrounded by long pine needles sticking out of the sand, you could only start your backswing above those needles (since they are all loose impediments)
Exception 1(b) under 13-4 says a player may place his clubs in a hazard without breaching the Rule. Dec 13-4/20 says umbrellas and rakes are the same as clubs, and 13-4/21 says throwing those into the bunker is the same as placing--however, 13-4/22 says "jamming" the rake (or club) into the sand is testing and is a breach--