During my last playthrough, I poisoned the goblins' grog bowl and waited just outside the main doors until I could see them dropping dead. I noticed Volo making a run for it and then went inside, proceeded to free Halsin, kill the goblins and loot the place. Afterwards, I went back to the grove, partied with the Tieflings and got the quest from Halsin to go back to the temple to find the entrance to the underdark.
After using the portal to go back to the goblin camp, I had to mop up the remaining goblins in the courtyard. While looting the corpses, Volo strolls back into the camp and starts yelling about a thief and questions me like I had just robbed him. As if that wasn't odd enough, the target value for the deception role was 0. After that, he just wandered about the camp and kept accusing me of thievery when I tried to loot a goblin. Very annoying.