I can’t speak for foone as I’d never heard of him before today. But I have asked people why they post long threads on twitter (because they drive me crazy too) and this is the exact reason they give. A link to a blog post is far less likely to get clicked than a twitter thread is to get read. It’s right there in front of you and you’ve already read the first tweet after all.
There is a patreon page linked right on his twitter page. He may not be exchanging time for food and shelter, but he is playing the same marketing game as anyone else for a personal high score.
linking to a blog he has to maintain would drop engagement off a cliff
Exposure to content is the reason HN exists and why you're reading it at all. If it wasn't posted on Twitter, OP may never have found it (even if a link to a private blog was posted to Twitter) and never shared it for you to read.