Couldn't you take this same line of reasoning and apply it to the rationalist group from the article who killed a bunch of people, and conclude that you shouldn't become a rationalist because you probably kill people?
And you wouldn't even need to know about the cult to reach that conclusion. One should be able to find crazy stuff by a cursory examination of the "Sequences" and other foundational texts. I think I once encountered something about torture and murder being morally right, if it would prevent mild inconvenience to a large enough group of people.