A message spreads on Twitter because individuals on Twitter amplify it (with engagement, retweets etc.) which is itself a form of speech: if you say something bad, and I retweet it, I am engaging in speech. Imagine a piece of land with 500 million people on it: a person 500 million people away from you cannot hear you, but if you say something and people choose to repeat it until it reaches that person… that’s Twitter. To prevent that is, in any framing, limiting free speech.
Twitter has some magical engagement-driving algorithms (for example, the homepage) but these are not the primary driver of engagement/reach on Twitter, so they could be removed entirely and this problem would remain.
So you’re probably right to say this isn’t a sudden 180 on his thoughts, but it still highlights how faulty his framing of free speech is.