>Is that a first amendment violation though if they voluntarily complied?
The entire point of the case was to determine exactly that. Read the judgement. If it were an open and shut case, it never would have made it to the supreme court.
>and that when they got in power they would be even worse. That seems vindicated
How in the world did you get to that conclusion from Murthy v. Missouri and the "Restoring Freedom of Speech and Ending Federal Censorship" order?
From the open use of the FCC to threaten television networks for saying things the president doesn't like? Among many other examples? That's just a particularly overt one.
I'm just saying overall behavior -- outside this specific case -- is not consistent with a regime (or a larger political movement) that believes in free speech. It's consistent with "we want to be the ones in charge determining speech," with opposition to Twitter's previous moderation being motivated by that rather than principled belief in free speech.
The net effect of the Twitter takeover was not to make it a free speech absolutist platform but to shift the pattern of selective boosting and selective de-boosting and moderation to one that favors the far right's message.