Because in the game's logic, stunned=dead. There are only a few specific situations where stunning results in something else. Enemies marked 'Temporarily Hostile' can be KO'd and they will return to life later. Or if the quest requires KO-ing someone, they will survive. Anyone else is dead so far as the game is concerned. If you want to 'save' any of her masked folk, you have to take her out w/o taking them down too. They will stop fighting when she dies.
