I thought I would post a video made by Nobbel87 that goves over the story of Rexxar, which has importance to the MU Stonemaul Clan:
Despite that importance and how Rexxar lead the MU Stonemaul Clan at one point, I feel like he would be better leading a Mok’nathol faction than the MU Stonemaul Clan again.
The MU Stonemaul Clan already has Tharg for a leader, and if not him, then Crol’ka, the Ogre who ran to Orgrimmar for help in Warcraft 3, could also become leader with some fleshing out. I personally don’t really see Rexxar having much interest in leading the MU Stonemaul Clan again.
If anything, I’d see him leading the Mok’nathol clan that his father lead. I assume in such a case, Rexxar and his father would make amends and eventually, Rexxar could take over it. This is something I imagine happening if we ever got Mok’nathol playable in some fashion.
I feel like it’s important for the leader of any Horde Ogre clan to be an actual Ogre. It fits the theme better, and in the case of the MU Stonemaul Clan, I can see it working a lot better in seeing how far they’ve come and having more meaning when it comes to Ogre presence. Having someone like Rexxar as leader again I feel like diminishes Ogre presence, making it feel like they don’t have the same level of membership in the Horde compared to other races.
This is of course my own personal opinion. Should we see the MU Stonemaul Clan pop up again in-game, especially if they lead the charge for the playable Horde Ogre faction, I feel like Rexxar should be there, but at best give his respect to whoever the actual leader of the MU Stonemaul Clan is as opposed to taking it over again.
Chances are, Rexxar would rather wander and live in the wilderness than become leader of any clan again. Still, it’s something I wanted to type my opinions on.
Dream big, Ogre fans! 
