Ask HN: Why do people like this get banned?

I recently turned on "Show Dead" in my settings, and have been seeing users such as this one: https://news.ycombinator.com/x?fnid=CVczXZH5Wb9GnOwIlOBszu

banned for no clear reason. His comments were all quite short, like another recent case I ran into, but not immediately thoughtless or argumentative. I could certainly find worse examples of non contributions in almost any topic. Is there some guideline at play that could be explained?

If I happened to pick a case where he was doing something shady that can't be seen in his comment history, feel free to ignore this. I'm specifically interested in knowing if there are non-obvious etiquette guidelines of which he ran afoul.