Especially as no one actually knows what that rule is. Does the team getting the drop ball have to touch the ball first? If so, West Ham could have just left the ball and run the clock out.
If they don’t, how long does a team have to wait before challenging for the ball?
As you say, he could have given the goal and no one would have known better at the time.
EDIT
Dropped ball
PROCEDURE
- The ball is dropped for the defending team goalkeeper in their penalty area if, when play was stopped:
- the ball was in the penalty area or
- the last touch of the ball was in the penalty area
- In all other cases, the referee drops the ball for one player of the team that last touched the ball at the position where it last touched a player, an outside agent or, as outlined in Law 9.1, a match official
- All other players (of both teams) must remain at least 4 m (4.5 yds) from the ball until it is in play
The ball is in play when it touches the ground.
Seems like Moss could have given the goal.