Why would Azshara feel the need to mind control a human (a race she'd regard the same way she would a cockroach) when she has hundreds of thousands if not millions of Naga who are so slavishly, almost religiously devoted to her that any one of them would ecstatically disembowel themselves (or each other) simply for her entertainment? She has to our knowledge literally NO interest in the politics of the mortal races whatsoever; so choosing to waste even a tiny fraction of her sorcerous power to mentally take over the leader of a comparatively small city-state of (mostly human and thus insignificant in her opinion) mages just seems like it would be massively out of character based on what we know of her personality.