I want to start off by saying that I strongly respect John De Goes and the decision he made. If you haven't already read his extensive post about what he did and why he did it, I highly recommend you take the time. His post is thorough and generally persuaded me to his way of thinking, which is not that the works of Moldbug should be accepted or ignored, but that we need to be inclusive of differing beliefs in a community, so long as the holder of those beliefs is willing to "leave them at the door". This is a strong, intellectually defensible and consistent position.
However, as the day has gone on, and I've discussed this issue at length with many members of the community. I have come to the conclusion that this is idealistic, and ultimately missing the point. And as strange as it seems, the point is not that there is a literal Neo Nazi who will be speaking at a well-regarded conference! The point is somehow bigger than even that, and it has to do with community.
Community is everything. I'm fond of saying that programmers are not automata, and that's true, but it radically undersells how important people are. Every time you "do the hallway track" at a conference, you're explicitly making the claim that the people at the conference are more important than the content. People often talk about how you should try to choose your workplace for the coworkers, not the problem. And when we punch our pillows in frustration after a difficult day, we're rarely thinking about a thorny technical problem or an annoying technology: we're thinking of a person (or persons). Community is everything.
And community is being disrupted. Not even by Moldbug himself, but by the idea of Moldbug being accepted in any form. I called this the "meta-controversy" on twitter, and the more I think about it, the more I've realized that it's the only controversy that matters in this case. Community is disrupted by Moldbug. It is now being disrupted by the announcement that he will be speaking at LambdaConf, and it will (presumably) be even further disrupted by the actual event. People are divided, some of whom believe that we can (as a community) divorce ourselves from these ulterior associations and judge solely on technical merit, and others who believe that allowing Moldbug a platform on any topic is benefiting and supporting his philosophy.
What I'm realizing is that it doesn't matter which of these opinions holds sway. The division and disruption of the community itself is the problem, and it needs to be rectified. This would be true whether Moldbug were the second coming of Hitler or of Ghandi. Social equillibrium is tremendously important, and disruption to that equillibrium is a cancer which the community must stamp out for its own preservation. Moldbug must be the recipient of this correction, not because of his views (which are reprehensible), but because of the effect he has. As horrifying as it seems, the fact that he advocates for literal slavery (and more) is secondary to the impact he has on the community as a whole.
The community must always act for the preservation of its own harmony. And to that end, I believe that Moldbug should be removed from his speaking slot at LamdaConf. All arguments about inclusiveness or the technical nature of a conference are an aside, because the community itself has decided that they are an aside by their reaction.
People are as free to choose not to participate in a conference as Yarvin is to espouse (or not) views many find objectionable. Decisions of whether to offer him a forum at a private event are not required to be made as though his personage as a presenter can be separated from his pseudonymous writings. I'm personally a big proponent of the idea that controversial ideas should be confronted, rather than silenced. But free speech as a societal principle does not include immunity from social repercussions in the private world. There's nothing authoritarian or maoist about that. And there's no particular reason to believe that Lambdaconf is the place where that confrontation should happen. Or even the genteel side discussion about programming, in face of the fact that one of the participants is also a considered a major thought-leader to many who hold views that denigrate the vulnerable and underprivileged.
That's an imposition on people who want nothing more than to attend a conference on a subject they want to engage in. The organizer of this conference has the unenviable decision of whether to impose that upon all the people who have done nothing in order to accommodate Yarvin. While I'm sympathetic to Lambdaconf's decision, it's certainly not for the reason quoted here.
I don't think there's a purely morally correct answer here. I think Lamdaconf made an admirable stand in favor of the idea of the "big tent". But I'll also not be surprised if the desire to make that tent big enough to accommodate Yarvin as a speaker makes it a lot less desirable for a whole lot of other people, and I don't blame anybody for deciding not to attend.