Exactly. From the K2 manual [0] referred to in the article, |/ is "Max-Over". The ostensibly-unreadable K manages in two characters what the article's subject and coworker need either three lines of boring loop or one line of a more cognitively-demanding lambda to accomplish.
...FWIW my understanding of the language is such that I would have suspected the last line of the article to read "|/ list". I thought Max-Over needed an argument.