So, has anyone besides me ever wondered why Darth Sion is not only Korriban when he seems to have no reason to be there, but happens to know you're there. It seems like a such a stupid and glaring plot hole and yet, very few people have noticed it. Well, I have a solution to this plot hole.
Simply add this scene right before you enter Korriban, but replace the exile with Vash. Then it could appear that he went there to capture Vash( having a purpose to be there before the Exile even arrives) and use her as bate to get the Exile. I think this is a good idea and could make for a good mod for someone to make. I'm wondering what you guys think? ( Also, yes I know this was originally intended for M4-78, but it has no purpose there. This scene could finally be used) Many thanks to Sith Holocron for helping me out with this idea on Reddit.