When I created the addon to the Silverwood way back whenever that was, goblins did not exist as playable race/class. The goblin is a ranger I do believe. There are other non-playable combinations in the game, that doesn't make it not possible for NPCs. I have no problem with the item being updated to allow raiders to use the quiver as well. I originally designed the character to help add more bows to the game as at the time it was still lacking somewhat.