Moldbug is leaving out the possibility that the balance of power might be changing, so that behavior which was too dangerous in the past is now worth attempting. Also, people's behavior can occasionally change the balance-- the Federal government was on King's side because a great many people worked to put it there.
Does getting assassinated say anything about one's power level?
That Communism would have fizzled in 1500 is a fact about the strength of non-Communist structures in the Middle Ages. That Communism succeeded in 1917 is a fact about the strength of pro- vs. anti-Communist structures at that time. Strength changes over time; that does not negate the fact that strength (probabilistically) determines victory.
http://unqualified-reservations.blogspot.com/2013/01/noam-chomsky-killed-aaron-swartz.html
Summary: Moldbug on the Aaron Schwartz affair. Power is a very real thing with real consequences for activists, yet many people don't understand the nature of power in modern times. People like Noam Chomsky get great fame doing bad epistomology about who has power, and as a result do great harm to idealistic nerds who don't read between the lines to selectively target their attacks at weak institutions (Exxon, Pentagon) instead of strong ones (State, academica incl. MIT).
Here he returns to a theme that is one of his real contributions to blogospheric political thought: that victory in political competitions provides Bayesian information about who has power and who doesn't. If your worldview has the underdog somehow systematically beating the overdog, your epistemology is simply wrong - in the same way, and to the same extent, as a geocentrist who has to keep adding epicycles to account for anomalous observations.
This means that activists like King, Schwartz, and Assange are only effective in bullying the weak, not standing up to the strong (despite conventional narratives that misassign strengths to institutions). When such activists stop following the script, and naively use the same tactics to attack strong institutions, reality reasserts itself quite forcefully: