I'm not sure about how this works in the US but in my country (Germany) "commercial use" does not actually require money to change hands or operating at a net profit. And last I checked copyright laws (if they apply to the content) apply to everything you create, whether you monetize it or not.

That HN comment of yours? If it's sufficiently non-trivial, it's protected by copyright. Even though neither you nor HN directly make money of it. If someone scrapes HN and republishes that comment, you could go after them and demand they delete it.