I prefer not to use email for most things because then the reply only benefits one person, whereas replies in a public forum can be read by others and get indexed by search engines.

I've been thinking about creating a Matrix room for each blog post as a discussion forum, but so far most posts have ended up on other discussion sites anyway.

To me it seems that the author doesn't list contact details on purpose. There's an extensive "about me" section without any contact information, so I think the author might wish not to be contacted.

Edit: actually, his Gmail is in one of the screenshots in this article.