Yeah, as HAL says, the issue is the footage. There’s no close-up footage of Palpatine saying “You’re nothing” like there is for the other two lines, which makes it very difficult to put last, because in order to cut to Rey for the end of the dialogue sequence we need to be cutting from somewhere else, and that somewhere else essentially has to be a closeup of Palpatine’s face. That’s why when I tried it in my mockup, I had to put the “you are nothing” line over the top of that footage of Rey - you can’t put it over the other Palpatine closeups, because the lipsync would be severely wrong, and you can’t use the wide shot it was originally over because that doesn’t lead into Rey recoiling from lightning correctly, etc.
Music can also be an issue: making the sequence significantly shorter means hiding a trim to the music somewhere (not super straightforward with the iconic Emperor motif), and even rearranging shots means harming how well that music syncs up to the action - assuming you can even manage to separate the music out from the sound effects in the first place (though this isn’t a total deal breaker if you’re willing to really go deep with reconstructing the sound mix and rescoring).
I think this thread has something of tendency to focus too much on the written text of a scene without checking the movie for whether it’s feasible. I’ve seen people (and not just Testing) repeatedly suggest materialising fairly complex new lines entirely out of thin air, even. You don’t need to actually be able to edit to ‘test’ your idea, you can just load up the movie, take stock of what shot coverage you’ve got and see in your mind if you could theoretically put it together or not. Many a good fanediting idea dies at the stage of realising you just haven’t got the right footage to pull it off.
To be fair, Sade also said in that same conversation that “I am a Jedi” wouldn’t feel climactic and that it probably couldn’t work believably.
To clarify, I was splitting the hairs between the somewhat trepidatiously-delivered “I’m… I’m a Jedi.” (which is what my mockups had) and the theoretical grand, defiant “I am a Jedi!” which I got the impression a lot of people were imagining. Achieving the latter line delivery would require a total replacement of the line using clips from elsewhere, as far as I can see. I do very much think “I’m a Jedi”, either my implementation of it or Sherlock’s, does work far better than “I am all the Jedi” ever did.
I was never 100% happy with my execution of that audio edit, but we’re all very critical of ourselves, especially when we’ve listened to the same audio clip hundreds of times. I mean, I still intend to use my version of that change in my own TROS fanedit; I didn’t mean to suggest it was unusable or anything.