It's not "castigating" or criticising potential users. It's advising founders not to waste resources attracting large numbers of visitors who are unlikely to be potential users, and instead do the hard work to attract and retain users who will actually value your product.
I made this mistake multiple times back in early 2010s "virality hacking" days, and man it was a painful and costly learning experience.
I don't read it that way. The hypothetical author here didn't "waste" any resources to make a viral video--it happened by chance. He got an influx of users from someone else's viral video, but he decided those people are "shitty" users because they didn't stick around and buy his product.
That doesn't strike me as maximizing long-term users; that strikes me as getting free publicity and being pissed off that it didn't attract the kind of customers you wanted.
I made this mistake multiple times back in early 2010s "virality hacking" days, and man it was a painful and costly learning experience.