I didn't particularly like either one. GPT starts off with clarity that it is Twitter's challenge, not a general discussion, which I'm not sure was your point. Actually, I'm not sure what your purpose was in either case, so that probably just follows.
Neither one acknowledges the weakness of the argument - it's simply false that most speech is permitted in almost any large private forum. There's both explicitly forbidden speech, and speech that is socially punished (by other users). Also, most venues are not take-it-or-leave it at a fine-grained level - you can leave entirely (as you can Twitter), or you can accept their bundle of speech that the venue and community allows).