https://www.lesswrong.com/posts/iWWjq5BioRkjxxNKq/michael-vassar-at-the-slatestarcodex-online-meetup seems to have happened after that point in time. Vassar not only attended a Slate Star Codex but was central in it and presenting his thoughts.
I organized that, so let me say that:
That online meetup, or the invitation to Vassar, was not officially affiliated to or endorsed by SSC. Any responsibility for inviting him is mine.
I have conversed with him a few times, as follows:
I met him in Israel around 2010. He was quite interesting, though he did try to get me to withdraw my retirement savings to invest with him. He was somewhat persuasive. During our time in conversation, he made some offensive statements, but I am perhaps less touchy about such things than the younger generation.
In 2012, he explained Acausal Trade to me, and that was the seed of this post. That discussion was quite sensible and I thank him for that.
A few years later, I invited him to speak at LessWrong Israel. At that time I thought him a mad genius—truly both. His talk was verging on incoherence, with flashes of apparent insight.
Before the online meetup, 2021, he insisted on a preliminary talk; he made statements that produced twinges of persuasiveness. (Introspecting that is kind of interesting, actually.) I stayed with it for 2 or more hours before begging off, because it was fascinating in a way. I was able to analyze his techniques as Dark Arts. Apparently I am mature enough to shrug off such techniques.
His talk at my online meetup was even less coherent than any before, with multiple offensive elements. Indeed, I believe it was a mistake to have him on.
If I have offended anyone, I apologize, though I believe that letting someone speak is generally not something to be afraid of. But I wouldn’t invite him again.
It seems to me that despite organizing multiple SSC events you had no knowledge that Vassar was banned from SSC events. Neither had anyone reading the event anouncement to the extend that they would tell you that Vassar was banned before the event happened.
To me that suggests that there’s a problem of not sharing information about who’s banned to those organizing meetups in an effective way, so that a ban has the consequence one would expect it to have.