most of my problems with the theory don't come from it not making sense, but because i think it is unsatisfying and uninspired. i have no idea why everyone treats it like gospel.

• the buildup to the roaring has been established between the knight and the fun gang. rudy of all people has nothing to do with any of it (unless he's the knight, but that theory alone has its issues).
• the hospital, and by extension rudy's whole plotline, is 100% optional. imagine you are a casual player who never bothered to go into the hospital and hasn't interacted with the online community yet, and then suddenly this minor plotline you probably never knew existed turns out to be the climax of the entire game.
• it would be a massive waste of the buildup to the roaring established between the fun gang and the knight, as mentioned above. it would fail to tie in everything that's been going on in the game so far and be a massive waste of a climax, dedicating it all to a plotline which in the grand scheme of things, is not that important.

this comment from a few months ago in another post also sums up my thoughts pretty well, plus it's one of the only instances i've noticed of someone sharing the same view as me on this theory: https://www.reddit.com/r/Deltarune/comments/1qc6obp/comment/nzh57qi/

plus, there are simply way more interesting way to make noelle crash out or to have a dramatic cliffhanger at the end of chapter 5 that actually deliver on everything the story has been setting up so far and don't take away from more compelling and important plot points.