not participating signals being apolitical; though participating would raise our status in some communities, it also reduces our perceived impartiality
Like with Wikipedia, the legislation threatens the viability/legality of LW in the US (and this would likely affect every LWer, even us non-US readers). Also, although not being protested, the RWA threatens a significant portion of open science, which could be far, far worse than just removing a website here or there (EDIT, however, this doesn't directly affect the existence of LW, so I feel the need for LW as an institution to protest is smaller).
So these laws are not necessarily something LW should maintain an apolitical stance.
Our sister site apparently is:
Interesting, my model of Robin Hanson had him say something about the blackout and how it shows people are hypocrites. Though obviously he has strong opinions on intellectual property. I think it would have been a good idea to Blackout LessWrong today. It would have given us a status boost in most of the communities we frequent.