> Also, if you're a company and you have a platform like facebook and Twitter, and you're a private company, not the government, you can kick whomever you damned well please off your service, or delete their posts, or edit them to make them look stupid.
According to at least some court decisions, this may not be true if you control enough of the public space to be effectively a "public square". This is what people are building their arguments around.
When the Constitution was written, there was a smaller population and towns had a clear center, so you could reach people effectively by standing on a soapbox on Main Street. That simply isn't possible anymore. Now that large corporate entities control both the physical public square (malls) and the virtual environment, there is nowhere left to set up a soapbox. This diminishes the natural right of free speech. There is an argument to be made that any entity large enough to constitute part of the public square should have to allow open access for people to stand on their soapbox.
Not an originalist take by any means, but that's not necessarily a disqualifier unless you're a strict constitutionalist.