That would make the canonical Master Death Knight in charge of the Ebon Blade an Alliance race, and I doubt Blizzard would do that for any class leader. Even if it makes the most sense for some. Like mages and paladins, because Blood Knights would be like "Stop wasting time praying and have this Sunwell water. It'll keep you charged up so we can go kill some demons without all this junk." And a Sunwalker would be like "Uhm...I can't fit through the door...can we move our order hall to Tyr's Hand or something? At least that's above ground..." and Horde race mages shouldn't trust the Kirin Tor at all, much less want their base to be there after taking command.