I believe he said it was Ajunta Pall. The Sith whose "tomb" contained the map to the Star Forge and no body. It could very well be that Revan and Malak were told by the Emperor to seek out the Forge, knowing that it would feed off them. And being rather arrogant(as has already been established in the Timeline) he figured they would actually listen to him. Instead they(well Revan at least as Malak was more destructive) began working against him. The Emperor might also have feared that the forge would take his force sensitivity as the Rakata had lost theirs(even though it was not the Forge itself, but I doubt the Emperor did much research into it...
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." Thomas Jefferson