Repeat after me:
Social media companies are not subject to the laws of free speech.
You're welcome.
Social media platforms are protected from liability for 3rd party content by BigGov. IMO, if they are going to get liability protection as a platform, that should limit their ability to filter legal content on their site. At that point, they are no longer just a platform. If they want to control the content on their site, they should get no legal protection from the govt.
Plus, I think their collusion goes a bit beyond just controlling the content on their sites.