You might want to try editing for style rather than references; the deleted text doesn't seem encyclopedic in tone, and doesn't mesh well stylistically with the rest of the article.
Specific things that stand out:
His highly popular story.
Wikipedia pages generally don't describe works as popular without reference. If a work is a bestseller or major cultural phenomenon, the page will make notes that effect, but you should try to avoid sounding like a fan plugging the story.
isn’t primarily interested in teaching readers the “what” of science
The story isn't interested in anything. You can describe the intentions Eliezer in writing it, but writing about what the story is interested in or intends sounds inappropriate.
even though it is liberally sprinkled with interesting facts about genetics, game theory, quantum mechanics, and psychology, among other things.
Sounds like what wikipedia would categorize as weasel words. "Liberally sprinkled with" is vague, and "interesting" is too subjective. Stylistically, you should also try to avoid using the passive voice (my parents both have degrees in writing and I hated it when they used to tell me that, but I have to admit that for most cases they were right.)
Instead, as the title suggests, it’s about the “how” of science, conceived of not in the narrow sense of research in a laboratory, but in the broader sense of the process of figuring out how anything in the world works.
It's not obvious that the title suggests this, and "it's" would probably be better as "Methods of Rationality is."
has been favorably reviewed by
Passive voice again.
The text does seem to be relevant and adequately cited for the content that isn't subjective, so those are the things I'd focus on.
Passive voice is unfairly vilified. I don't like it when it's obviously serving to avoid citing the agent of an action, but consider that "Z has been Yed by X" or "X has Yed Z" give the same information. If you look at the best writing, you'll find some passive constructions.
Mostly, people can't reliably identify passives - see especially these amusing (not unusual) "passive voice" corrections, although in your case you accurately identify it (except maybe you could call "X [is] sprinkled with Y" an adjective complem...
For the last few weeks, I have been engaged in a slow motion edit war on the Wikipedia Eliezer Yudkowsky article, about including discussion of HP:MoR. The specific text being removed, to my eyes, well-sourced and germane to the article. But it may be that only 2 reviews of it is not enough and the other editor will respite if I can add in another RS or two.
Of course, I don't know of any besides the ones I have. That's where you all come in. What can I add to bolster the case for inclusion?
(If this seems trivial to you, I will note that the WP article gets around 2000 readers a month, and will continue to do so indefinitely; the WP article is also ranked #3-4 in Google for "Eliezer Yudkowsky". My impression is also that people reading WP articles tend to be 'high-quality' visitors, who spend time reading it and whose opinions are molded by it. At least, I've noticed this with Evangelion articles - points and quotes I've spent time referencing and highlighting tend to show up in reviews and other mainstream coverage...)