I'm of the opinion that their post is still human-written. They describe in their first blog post that it's human written (which could be a lie, but oh well) and their other blog posts seem to have the same informal lowercase hyphenated writing style. Sentance length varies throughout the posts. Sure, you could prompt this writing style, but I lean towards thinking that the piece is human written.

This reads nothing like any AI text I've read before.

This is pretty clearly written by a human.

I also have the impression that the writing was at least "enhanced" with an LLM. For example, the amount of " - " dashes (over 60) is much higher than in a normal text.

By the way, I consider it a pretty disgraceful defect of HN that people routinely "flag" opinions merely because they disagree. The flag is for spam, not for downvoting.