That's not the first time I've heard LW referred to as a neoreactionary site, though; once might be coincidence, but twice needs explanation. With the survey in mind it's clearly not a matter of explicitly endorsed philosophy, so I'm left to assume that we're propagating ideas or cultural artifacts that're popular in neoreactionary circles. I'm not sure what those might be, though. It might just be our general skepticism of academically dominant narratives, but that seems like too glib an explanation to me.

Viliam's explanation seems like a strong one to me, but doesn't explain the historical accident of (to use his made up numbers) half of neoreactionaries reading LW.

I suspect that LW has a vibe of "actually think through everything, question your implicit assumptions, and follow logic to its conclusion." The neoreactionary believes that doing so ends up at the neoreactionary position- even if that is true for only 1% of people, that leads to a 10X higher concentration of neoreactionaries at LW. At the very least, it seems that LW has a strong tendency to destroy strong political leanings, and especially affection for popular government-supporting narratives.