That's because the Dark Side option where you beat the crap out of him was actually supposed to kill him. Have you considered that perhaps the continuation of the Sith Warrior story will address this? You are, after all, asking about story content. It doesn't happen over night.
Yes I'm well aware that story content takes a large amount of work to implement and would love to see this continued although I highly doubt anything will come of it so I will just brood over it :P