I have to agree with him on all points here, and so once again the Twitter rules of engagement are breaking down. Particularly, I must agree that we should not tell other people how to manage their own patch of cyberspace, whether it is a blog, a personal Facebook page, Twitter feed, or what-have-you. To each their own, may they make of it what they will.
However, it must be said that the character of the forum reflects upon the character of the moderators. I used to be very active in an online forum wherein the only rule was "Don't be a dick" and the interpretation of that rule was entirely at moderator discretion. At the same time, I was somewhat active in another forum with essentially no rules of engagement: a place loaded with gun nuts, racist assholes, and unsubtle death threats. Oftentimes some of same people would behave very differently in the two places, because they each had their own culture and rules of engagement.
Bloggers should not be told how to manage their comment threads, but neither should they expect not to be judged by the character of their commentariat. If you are hosting threads which proudly propagate memes such as "Fuck yourself sideways with a decomposing porcupine" then you may be assumed to have very different goals and values than someone who puts in place a comment moderation policy carefully designed to foster a "constructive, far reaching dialogue and philosophical debate" free from unnecessarily demeaning remarks which generally hamper rather than further substantive debate.
One final point. As an avid consumer of high-end freethought content, I would much rather attend conferences where I can reasonably expect people will not be verbally harassed and abused, just as I would much rather read online forums where those same expectations will be maintained and enforced. I'm not in a place to tell conference organizers or bloggers whether or how to create spaces in which a proper balance is struck between free expression and anti-harassment, but as an individual, I can choose not to patronize those who do not even try.