[Elgin Clock]

While this situation certainly falls under a "gray" area of the rules, I would call it as being scored even if it fell off.
The reason, is that once scored, a moon rock can not be de-scored.
(Re: Fallen trailers)
Also, there is no rule that explicitly states the moon rock has to be contained within the pvc pipes on the outside.

SCORED: A GAME PIECE is SCORED when it is fully supported by the TRAILER or other GAME PIECES that have been SCORED.

Supported by the trailer? Yes.

Although, <G07> COULD contradict the ruling about Fallen Trailers& also this scenario, I myself as a Ref would override the statement in <G07> rule in favor of staying under the consensus of the Fallen Trailer rule <G01-B> & say this one is scored as well, even though it fell off & onto the playing field.

<G07> Scores are determined based on the state of the GAME PIECES at the end of the MATCH.
Scores will be assessed after all objects in motion when the arena timer displays zero seconds
come to rest.
A. The final score of a MATCH is the total of points assigned due to SCORED GAME
PIECES, less any assigned PENALTIES.
B. If a TRAILER tips over, the points SCORED for that TRAILER at the time it was tipped
will be preserved for the remainder of the MATCH.

If it fell out, & was scored AGAIN by another robot in another trailer, that would also count in my opinion just as other scored moon rocks that fall out of a Fallen Trailer would count... or would they??

If a Bluabot should bump into the trailer, knocking the moon rock off its precarious perch and onto the floor, should they be penalized for de-scoring?

No.

What if they are pushed into the trailer by another robot, red or blue?

No.

Of course, this is all my opinion, but I believe this is all following the spirit of the game.

Btw, did anyone get a pic of it sitting on top of the trailer?