There's no need to cancel anyone who's failing to have influence already.  I suspect there are no apolotical test cases: cancellation (in the form of verbally attacking and de-legitimizing someone as a person, rather than arguing against specific portions of their work) is primarily politically motivated.  It's pretty pure ad-hominem argument: "don't listen to or respect this person, regardless of what they're saying".  In this case, I'm not listening because I think it's low-value on it's own, regardless of authorship. The manifesto is pretty easy to find in PDF form for free.  I wasn't able to get very far - way too many crackpot signals and didn't seem worth my time.  To your bullet points: 1. I can read this two ways: "should anybody" meaning "do you recommend any specific person read it" or "do you object to people reading it".  My answers are "yes, but not many people", and "no.".  Anybody who is interested, either from a direct curiosity on the topic (which I predict won't be rewarded) or from wanting to understand this kind of epistemic pathology (which might be worthwhile) should read it.   2. It's absolutely acceptable.   I wouldn't enjoy it, but I'm not a member of the group, so no harm there.   To decide whether YOUR group should do it, try to identify what you'd hope to get out of it, and what likely consequences there are from pursuing that direction.  If your group is visible and sensitive to public perception (aka politically influenced), then certainly you should consider those affects.

To be explicit, here are some reasons that the EA community should cancel Kaczynski. Note that I do not necessarily think that they are sound or decisive. * EAs are known as utilitarians who are concerned about the impact of AI technology. By associating with him, that could give people the false impression that EAs are in favour of terroristic bombing campaigns to retard technological development, which would damage the EA community. * His threat to bomb more people and buildings if the Washington Post (WaPo) didn't publish his manifesto damaged good discourse norms by inducing the WaPo to talk about something it wasn't otherwise inclined to talk about, and good discourse norms are important for effective altruism. * It seems to me (not having read the manifesto) that the policies he advocates would cause large amounts of harm. For instance, without modern medical technology, I and many others would not have survived to the age of one year. * His bombing campaign is evidence of very poor character.