Since you've read the site guidelines, you know that HN is for stories that gratify intellectual curiosity. The curiosity in this case is of another, more intense nature. And you also know that purely sensational stories are deprecated.

It's true that the moderation comments that I post are off-topic, but they're the only way we know of to really disseminate knowledge of how the guidelines work in practice, and there's a clear demand for that information by users. So the judgment call is that their benefit is greater than their cost, even though the cost is nontrivial.