Most online petitions are already doomed from the beginning. But a petition where they ask fucking elongated cuckrat to do something that would absolutely go against his ego... Yeah, this won't be happening.
So use Mastodon. Problem solved. Twitter is toxic. You can't fix Twitter without fixing the whole culture.
Getting rid of Elon (in some hypothetical universe where you could do that) & restoring the site's design back to what it used to be isn't going to change the toxic culture. Twitter only selectively enforces their own rules and it's been that way since Jack Dorsey was in charge.
(Here's an example: I can think of a few tweets where people are ganging up on someone and those are still there to this day. Their rules are very clearly 'no harassment and no dogpiling' and they've always been that way. Do you think they give a damn to enforce their own rules? Only when Elon's right-wing buddies are being attacked, then they bother.)
Restoring the site's design back to what it used to be isn't going to magically fix the toxic culture (people sniping, dogpiling, attacking others etc). Better if we just set the whole thing on fire and start from scratch, build something new - oh wait, we have that. It's called Mastodon. The learning curve isn't that bad. But that would be learning something new. That would be actively doing something other than complaining.
Why would you want to back to a place where a billionaire or a corporation collects all your personal data? If you like that sort of thing, go to Threads, Bluesky, Post, etc. Nobody's stopping you.