An LLM was used to help polish the text, and that section probably got over-polished. The ideas and code are authentic. The article is intentionally detailed for those who want the full reasoning, but you can always skip straight to the source code.
Out of curiosity what particular part of the original text needed to be polished and why couldn’t the writer accomplish said polish without a language model?
When writing the articles in that series, the focus was more on getting the technical ideas and details right, not on spelling, grammar and text flow in which LLMs excel. That specific section "Why this maps to Genetic Algorithms?" makes the point that the fit of Genetic Algorithms to state space exploration is not a coincidence, and argues that the evolutionary process itself is a state space exploration algorithm that allows a given species to advance further down life's timeline. But thanks for the question, I do agree that as LLM generated text becomes more ubiquitous everywhere, we all do appreciate more our own human writing style even for the highly technical text where the focus is on the technical ideas and not so much on the presentation language itself.