I assume some tribes on MU Draenor used boars for various tasks, especially since we see some utilizing them in AU Draenor. We don’t really see any of the clans on Azeroth with them since the model wasn’t created until WoD became a thing, but that can always change.
It’s possible those boars are there because it was considered an updated model and placed on Exile’s Reach because of it as opposed to lore reasons. Kinda funny that it opened that line of thinking as a result, but it’s still an interesting thought.
It’s a pretty awesome sight. It also makes sense, seeing as some of the Ogres on AU Draenor are riding them as mounts. Add some armor to the mount and toss the AU Stonemaul Clan in with the MU Stonemaul Clan, and it solves a number of questions about playable Ogres. Not all questions of course, but several of them. 
Dream big, Ogre fans! 
