Section 230 makes it clear that these companies aren't considered speakers of their user posted content, hence preventing them from moderating it doesn't impose on their free speech since the user posted content isn't considered their speech.
It sounds like his argument is that moderation isn't speech, and the posts on these sites, due to 230, aren't attributable to the would be moderators, therefore the tech companies don't have a right to claim that their first amendment rights have been breached. I'm unsure what the caselaw on site moderation looks like, so i have no idea if the assertion is correct
