I'm not entirely clear as to the actions of Green 10. He's allowed to fall on the ball to secure it - but your description is rather different - he dived to the ground NEAR it, and then just lay on the floor on the Red side of the ball? Without touching it?
If that is the situation, I think you had a very rare beast indeed to deal with - no wonder you felt clueless! You'd doubtless suffered contagion from Green 10!
[LAWS]Definition: Law 14 - The Game is to be played by players who are on their feet. A player must not make the ball unplayable by falling down. Unplayable means that the ball is not immediately available to either team so that play may continue.[/LAWS]
That principle underlies the whole of the "player on the ground, no tackle" Law 14. Specifically, Law 14.1(c)
[LAWS]c) A player without the ball must not lie on, over, or near the ball to prevent opponents getting possession of it.
Sanction: Penalty kick[/LAWS]
So PK.
However, it he had indeed gathered the ball, then set it back and released as though there had been a tackle, I wouldn't see his continued presence there as any more objectionable as it would be if he had indeed been tackled. If you'd ping him at a tackle, ping him under Law 14. Otherwise, play on.