Wrong wrong wrong, the First Amendment does NOT cover this at all.
No, I'm not wrong. I believe it was Marsh v. Alabama that set the initial precedent and that was subsequently expanded to property owned by a shopping mall (can't remember the case on that one). Both of those were SCOTUS but then there have been multiple state supreme court rulings affirming free speech rights on private property despite objections of ownership when those properties are considered to be "public square" (primarily shopping malls). I'm not Alex Jones, I don't just make up facts.
Now, I could also see a compelling argument building on these rulings that there is a digital equivalent to the public square and internet platforms that are normally open to the entirety of the public and of sufficient size and reach would have to adhere to that same doctrine.