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.
It is human written and i've thoroughly went over every paragraph but i did use some help with wording. i suppose it does show now that you mention it
The fact that terms like Aho-Corasick, PLDI, Go, etc. are properly capitalized, including if they begin sentences, but otherwise sentences are uncapitalized, makes me think it's an explicit LLM instruction "don't capitalize the start of sentences" rather than writing style.