There's much missing out of your sentences too!
So?
Considering there was a wide variety of ways for that to play itself out, much of it had to be accounted for in some way, in a variety of different ways.
Star Forge went kaput.
Who cares about Manaan...it wasn't important to your quest. What difference would it have made if it was destroyed or not (again, many things could have happened here in KOTOR 1, which makes designing around it more difficult)? You never go there, as you never have a reason to. Heck, it's possible the Exile had never really heard of Manaan.