The only problem I can see would be the minor irritation of having him say "something smells foul..." every time you let the laundry pile ...
But wouldn't it be his job, as steward, to see the laundry is done? Along with getting me a few chickens, finishing the kitchen wing, buying groceries, and cleaning the stable?
But I agree - Kharjo is my favorite follower. And after I built my estate near Morthal, he's great for slaughtering the bandits that keep spawning there. Too bad he can't be steward, though.