I also keep coming back to the fact that he has chosen to approve his comments. I struggle with this because he seems to have a legitimate reason for this choice and he is still letting the dissenting voice through but, like he expressed, this represses dialogue which I think is one of the strong areas of his blog (peoples want to comment on it). To me the good is out weighing the bad. He has created a great platform for discussion, I'd really like to see him open up his comments just to see what the result would be. Beside increase in traffic I think that it would also increase the quality of statements.
I see that the writer’s value in free-flowing information creates a bit of an ethical dilemma. However, you really need to consider that fact that free-flowing information which is quite unorganized really stands in the way of effective communication, which is a closed-looped system.
Since Professor Jacobson’s niche is really a unique and organized opinion on politics, open comments really diminish the content. In communication, interference is the most common way messages are not received. Comments that do not provide a value-added benefit to Jacobson’s post could dramatically hurt his content. If everyone were sabotaging each other’s comments section, no one would bother reading political blogs, thus no one would bother writing a political blog.
This may be a bad example since Paul Krugman’s credibility is highly questionable in comparison to William Jacobson, but American Thinker points to the truth of this argument with regards to Krugman's blog at the New York Times.
Now, you should really consider two nuances to comment moderation and blogging in general.
First of all, if Professor Jacobson is moderating all comments, then he is reading all comments. This means that a) he’s more likely to be in-tune with the readers than myself (who does not use it) b) every comment is guaranteed to be read by the professor. Thus, the whole world may not see your rebuttal in the comment’s section, but you can be sure that it won’t be overlooked either
Second, free-flow of information is presevered by the existence of blogs with opposing views. If you find a flaw in a bloggers message, usually, it makes for good blogging content. Inventions like trackbacks for wordpress all but guarantees that you can attach your opposing view to the blog with the original idea and the author can’t do much about it. But, more importantly, an innocuous trackback does not deter from the message of the original posting, while providing an opportunity for dissent.
So feel free to moderate comments without worrying whether you are enacting Pravda style censorship. The freedom of the internet prevents blogging dictatorships.