Quote Originally Posted by Sir Bahamut
Ellone says the past can't change.

Hence, whatever Odine would have done wouldn't have changed a thing. Kill Odine? The machine would still have been built somehow, because since the line of time in FF8 never changes, Ultimecia will ALWAYS get hold of the machine.
She says it won't change through "time travel." The doesn't exclude changing the outcome of what may be after knowing what would be.