The comment I linked incidentally happened to be (understandably) stuck in my head, but some bumbling around and experimentation with Algolia for a few minutes (trying keywords like "works at", "engineer" and "dev") also found https://news.ycombinator.com/item?id=29700627, https://news.ycombinator.com/item?id=12924580, https://news.ycombinator.com/item?id=12928349, https://news.ycombinator.com/item?id=20701499, https://news.ycombinator.com/item?id=19815847, https://news.ycombinator.com/item?id=16971725, https://news.ycombinator.com/item?id=3587191, and https://news.ycombinator.com/item?id=4728531. It's quite possible none of these are relevant or useful; I also just thought of https://github.com/search?q=tumblr&type=users, which surfaces an interesting level of signal right on page 1, and this is not even mentioning LinkedIn, notwithstanding that site's caveat of "oh no" vs "likely most direct solution to problem" :)
(Now to work through this small pile of unrelated interesting things that also mysteriously opened themselves over the past few minutes. Welp. All good :D)
I sent an unsolicited email to the person above, and was polite about asking, but no reply yet :)