Re
It is common sense, just as an opponent would not gain AOO's against a table in the room, they don't gain an AOO against an unconcious person.
Coup De Gras action more than makes up for not getting an attack of opportunity as well as the excessively low AC the unconcious person will have if they do decide to expend all their attacks on the unconcious person.
How is Hold the Line Feat different? How often is the situation you describe going to apply?
If the unconscious person is threatened by an active combatant, there's no need to "jockey for position" and "look for open shots". There's no "leaving openings in defences", because there are no defences. The attacker can flail away as fast as he likes, and there's nothing to stop his shots getting through, no need to dodge, to guard against return strikes.
It is common sense, just as an opponent would not gain AOO's against a table in the room, they don't gain an AOO against an unconcious person.
Coup De Gras action more than makes up for not getting an attack of opportunity as well as the excessively low AC the unconcious person will have if they do decide to expend all their attacks on the unconcious person.
How is Hold the Line Feat different? How often is the situation you describe going to apply?