This theory is unlikely, and unnecessary.
Elon donated some $277 million to the Republicans during the 2024 presidential campaign. You aren't going to be dumping a donor like that.
While Elon has relaxed rules for banning people from X, I do not for one second believe he doesn't tilt the scales on his site. The amount of totally real, not fake, accounts that parrot the same insane shit he does is just beyond belief. Whereas on other sites these opinions are far less common and always contested.
He's had a huge influence, by arguably nefarious means, but there's nothing suggesting he faked votes.
You can just as well hack an election by taking control of the "public square" and stop it from being a hug box/echo chamber for Party A and turn it into a hug box/echo chamber for Party B by fucking around with da rules and da algorithm as you can by faking votes.
One could also argue by removing Party A hugbox mode, the pendulum naturally swung and Party B became dominant in a form of natural selection.
Given the insane amount of bot/shill accounts that talk and parrot about political viewpoints (as you hinted at) it is effectively impossible to tell if he deliberately altered the algorithm to achieve a certain outcome.
And this isn't just a theory that the election outcome was heavily influenced by the takeover of Twitter, I've read several prominent people who are fairly apolitical come to the same conclusion. And that's because Twitter is faster and more effective than the old form of mainstream media (TV networks etc). Taking over Twitter and repealing or adjusting the ruleset to possibly deliberately allow for certain news stories and points of view to dominate means you're working with something that is "bigger" than the typical mainstream media network.
Again it is really hard to know how much of that plan was deliberate given the also opaque censorship that had happened for ages against certain political views - even if not-Musk had taken over and removed the old Twitter rules and tons of their staff and didn't change things with any specific angle towards any political party (ergo: "I want to see trannies and rednecks and COVID truthers fighting, don't ban any of them, this shit is hilarious" a.k.a. "the KF approach") the outcome may have been the same.
Part of the reason "tech leaders" are giving Elon so much credit in all of this is both because they were sick of how controlled Twitter had become and also perhaps because they believe he had a very deliberate plan all along. But given that Musk was essentially forced into buying it (which is still debatable since he seemed to mostly be bitching about the purchase price) it remains to be seen how much foresight he actually had with all of this.
It is definitely entirely within the realm of possibility that there were meeting with Trump ahead of the election where he negotiated what he would want post-election if he secured the win for Trump via owning Twitter.
Whether or not he has true foresight will depend on if "X" actually becomes an "everything app" in any rapid timeframe.
One thing is for certain, by injecting himself so heavily into politics and also being the world's richest man he has cast a very large shadow and a very large profile and the violent rhetoric I see against him on a near-constant basis is alarming to say the least.