There's a difference between, on the one hand, knowing who they are and having read a few chapters of HPMoR, which I agree is standard for anyone who spends enough time on the Internet, vs. on the other hand actually identifying as part of that culture. I know who Stallman is, I've even seen him speak in person, but I'm not a GNU zealot.
The people described in the article aren't just "people who know who Yudkowsky is", they're self-avowed EAs and active LessWrong members.
The people described in the article aren't just "people who know who Yudkowsky is", they're self-avowed EAs and active LessWrong members.