Originally Posted by Redeemed Jedi
I say that he never did die, even though the novel says so, but that he severed his connection with the force; hence the force blast that occurred. By doing so his presence in the force would not be possible to detect (Yuuzhan Vong ring any bells) which is why the two dark lords thought he was dead.
Well both are very possible...I think they kept him alive. Palpatine is no fool and would use Starkiller as means to an end if he had the chance too. Like he did in the Dark Side ending.