For Musk to get out of it he has to find a materially adverse effect (MAE), which is incredibly difficult and almost never happens. As Matt Levine explains in the article, it basically has to mean that Twitter is a complete fraud and has been covering up a fraud for a long time (think Enron), which is very unlikely given that users obviously use it, and advertisers obviously advertise on it quite happily.
I'm tired of people parroting this line. It is factually incorrect. This line has been started by the author of the article we are discussing, and picked up by people who like the way it sounds, but if you'd read the article the author also clearly states (significantly less dramatically) that he has an out if Twitter lied because that would be breach of contract. He goes on to say there's no evidence that Twitter lied, which may be true, but it's a fact. If twitter lied about their numbers it is a breach of contract, MAE be damned.