'Justice Brett Kavanaugh wrote on behalf of the majority that, while the First Amendment's free speech clause applies to "state actors" or governmental entities, the network is a private entity, not a state actor: "Providing some kind of forum for speech is not an activity that only governmental entities have traditionally performed," the decision reads. "Therefore, a private entity who provides a forum for speech is not transformed by that fact alone into a state actor."'

https://psmag.com/news/a-supreme-courts-decision-could-have-implications-for-social-media-free-speech