Love this 5th circuit decision as it dismantles the "Companies can censor because its their free speech". If they are actually speaking, yes. Social media companies are not.
The speech on social media sites is user speech, not the companies. There is no "compelled speech" when you merely transmit another's speech. Sometimes a publisher exercises "editorial discretion" over what content they choose to publish. So is this what a social media company is doing if they ban a post? No. The court found social media platforms "exercise virtually no editorial control or judgment."
The 5th Circuit found two problems with the editorial discretion argument. "First, an entity that exercises 'editorial discretion' accepts reputational and legal responsibility for the content it edits." Social media companies do no such thing. "Second, editorial discretion involves 'selection and presentation' of content before that content is hosted, published, or disseminated." Social media companies generally publish first and censor in response to user reports. This might be different in smalll forums with active moderators, but the large sites make no such effort. So if you want to be treated as having free speech by virtue of editorial discretion, you have to actually do work, like say editing, that changes the content up front. Both points come with many caselaw legal citations from Supreme Court precedents that seemed pretty rock solid to me.
States have the authority to define rules when companies are more like "common carriers" than editors, according to the 5th circuit.