Look at it this way: The benefit is essentially heroism, which is a 3rd-level spell that only affects a single ally. Since this is effectively "mass heroism", it's probably the equivalent of a 6th-level or higher spell. That's probably way too much for a creature of this power level to use at will.
I'd recommend either limiting it to 3/day (non-stacking), or making it require a standard action each round for the genie to maintain (barking orders, waving flags, and whatnot). I kinda like the latter, as it makes him even more of target, and explains why it ends if he is taking down.