Dan is a good writer, to be sure. And he definitely has opinions. Is it bad that he expressed those opinions in such an incindiery and provocative way? Or is it just effective writing?
I think that since a worse writer might not have elicited as many strong reactions on the blog. In this sense, the piece of writing was effective and well-done. Good writing doesn't need to be respectful, polite, or politically correct for it to be good writing. That is important to remember. Being able to offend someone means that your communication has a certain degree of emotional power.
Should we only look up to and idolize writing that is respectful and polite?