On Goblins: That explains it then. Doggy-Style skills at the lowest possible Charisma stat of 1 is able to make them submit within four rounds but Nelson/Grapples lack the charisma boosted skill. The only skill that isn't able to make them cum repeatedly at every turn is the standard 'Pound' skill.
On Warlock: Well even if it's just a place-holder I still liked the presence of it being there.