They can use the Lord Draahg method, our Sith Inquisitor/Warrior also came back from near death and the enemy thought we were dead. It's not a big deal and the Empire already lost many cool Sith.
Bringing him back to life isn't the problem, Star Wars have pulled that off more times than I can count. It's making it fit that is difficult. If BioWare were to do what you suggest, it would create two parallel stories: one were Tormen dies and is brought back to life, and one were Tormen lives. (It would also make Tormen and enemy of the BH - and judging by his character he would go out of his way to kill you)