once again slothus very much possible. if you look at the new star wars book about locations and it goes into detail about that med facility that palpy fixes ani there's a lot of sith going on in there. and going into the use of dark energy and all that is possible it might make it a little confusing or drawn out if it was in the movie. while the emporer is a master manipulator and sees a lot into the future he is also very overconfident and arrogant. i think that the emporer never saw it coming that vader would ever turn back to ani, he pretty much wrote off the whole Chosen One thing.