I worked for newspapers for a good part of my career, and I have a kind of newspaper attitude toward websites -- that is, the owners/publishers control the website and are responsible for what appears on it. There is a serious "responsibility" involved. In practical terms, though, websites can't be run quite like newspapers, because with a newspaper, ALL the content first goes through the hands of an editor. That's simply a practical matter of newspaper production. On a very large website with a forum, with automatic, self-selected publishing, it's somewhat impractical to have somebody sitting astride the commentary at all times (although some smaller websites, like The Online Photographer, do that.)
The point is, eliminating some commentary isn't (in my view) a restriction of freedom of speech. A website owner who stops an argument, locks a thread, or bans some commentators is not saying, "You can't speak," he's saying, "You can't use my website to promote your views." That's just like Target or WalMart saying, "You can't set up a soapbox and speak in our store." You're free to go anywhere else that you're accepted, or to set up your own website, and broadcast your views any way you wish -- you can speak as loudly as you wish, to whatever audience you can attract. But a website owner can say, "You just can't do it here."
Michael runs a pretty loose ship. I've been on this forum for several years, and it appears to me that's because of a conscious philosophical position. If I were running it (and thank god I'm not) I would be somewhat more restrictive. Not much, but somewhat. The Schewe-style exchanges don't bother me, but some of the exchanges that we saw in the late unlamented medium-format thread did bother me, and I would have shut the thread down much earlier in the process, and would have also have closed down any revivals of it. That said, I have no problems with the way Michael handled it.
But still, and to repeat myself, IMHO closing a thread, or banning a commentator, is not limiting free speech, nor is it censorship, any more than removing a disruptive child from a classroom is. It's simply taking responsibility for controlling the website. The disruptive person is free to make whatever speeches he wants, to whatever audience he can find...elsewhere.