Sure, you can rationalize it in-universe, at least within the context of the sequel's universe. I'm looking at it more metatextually, thinking about the differences in intention between the original filmmakers and the sequel's filmmakers. See, I waited to see Legacy
until I could get my hands on a copy of the original, so I could watch them on consecutive days. And that turned out to be a mistake, because it just highlighted all the differences in concept and approach between the two. Back to back, the two films just don't feel like they go together. The changes were kind of jarring.
But you make a good argument. Maybe in the future I'll have a higher opinion of Legacy
. But I'm not sure it lives up to its name. It's too revisionist, too different in approach, to really feel like it's carrying on the legacy of the original.