Those people were responding to arguments that social media platforms banning people, moderating content or even presenting content under an algorithmic feed were violations of the First Amendment, Section 230 and freedom of speech, by pointing out that all of these actions are allowed by the aforementioned principles and laws.

And notwithstanding that Twitter banning journalists (even for just 12 hours) is a much more serious deal in terms of freedom of speech implications than banning some shitposting Nazis, no one complaining about that is actually claiming that Elon doesn't have the right to do what he's doing, nor are they calling for the government to make it illegal - they're just calling him a hypocrite and an asshole.

This really isn't the dunk you and the countless others who keep bringing it up is, it just demonstrates that the "free speech absolutist" crowd were never arguing in good faith to begin with, because none of them ever bothered to actually listen to or engage with the arguments being made.