If you take a look at the comments, it's theorized there that the story got pulled not because of moderator action, but because people abused the flagging mechanism. Given the content, and given the principal person under discussion, this seems pretty likely to me.
Why would it be abuse if people flag it as being off-topic for HN? The article is about some community code of conduct text which the article author comments on by adding their own interpretations to it. It look political and it uses inflammatory language.
The tug of war between upvotes and flags, as commented by dang, seems a strong sign that the article is very much political in nature. The question is if it also gratifies one's intellectual curiosity, but personally, in this case it did not do that for me.
I'd say tech culture is 100% fair game for Hacker News. In fact, it's been the subject of a fair number of front page articles recently (look at the Fowler stories, for instance). The flagging suggests to me that they didn't like what was being said, rather than they thought it was off-topic.
A good test for this that the moderators could run is to see if those that flagged this article flagged any other articles about LambdaConf's policies and if so, which.
Another one is to compare its performance to other, similarly political articles by the same author (e.g. his free software posts) and see how they performed.
If you take a look at the comments, it's theorized there that the story got pulled not because of moderator action, but because people abused the flagging mechanism. Given the content, and given the principal person under discussion, this seems pretty likely to me.