So I can’t delete comment spam on my public blog as that would violate “free speech”? I also don’t need a Facebook account in order to post content and consume

So I can’t delete comment spam on my public blog as that would violate “free speech”? I also don’t need a Facebook account in order to post content and consume it? You are missing the point about Marsh v Alabama: unrestricted public accessibility vs the private club with authentication and exclusion built into its very core. Rockefeller center, though a “public” space closes and excludes the public for around 5 minutes annually to prove that it is not a truly public space and so they can kick anyone out at any time for any reason. Facebook’s registration and authentication does the same. You publish at their pleasure. In marsh, the equivalent would be a velvet rope around the sidewalk where only approved and registered people could enter, view and express their opinions. Facebook is emphatically not the public sphere, as much as y’all want it to be: it is allowed exclusion of anyone according to its own choosing. That it can ban someone and delete their account makes Facebook not a public sphere. Same as my blog: your comment stays up if I want it to, no implication on the right to free speech.