I can't answer for cloakandswagger, but GPs comment sounded to me like this blog post is missing something essential because it doesn't talk about security.
This isn't an expensive course on setting up the perfect ES cluster in production.
As someone who is currently planning to set up a substantial ES cluster, I'm very grateful for someone to write up their learnings in such a compact overview.
What's your point? The ops side of anything also covers security. In fact, you cannot have ops without effective security.