Your timeline does not hold up to scrutiny. The Media Matters report came out on Nov 17, 2023. Musk was tweeting support for antisemitic conspiracy theories prior to that. The one that got the most reaction was on November 13. But Musk had been feuding with the Anti-Defamation League for months at that point. And as a result companies like Disney and Apple had already been pulling ads from Twitter prior to the Media Matters report.
Perhaps the Media Matters report increased the momentum, but the problem was one of Musk's own creation. He created the problem, and the atmosphere that allowed Media Matters to even get noticed. He would love nothing more than to take the blame off himself by trying to blame others.
That he wants to do that by silencing an opposing voice also demonstrates his hypocrisy when it comes to being a free speech absolutist.