staying away from discussions of emotionally charged recent news

That's a strawman. Nobody argued here that it's bad to discuss recent news in general.

That, essentially, the idea that tabooing discussion of things that are emotionally charged is a way of tabooing a valuable part of learning to be less wrong .

That's not what "politics is the mindkiller" advocates. It advocates not using emotionally charged examples to make points that you could make with examples that are less emotionally charged.

If the OP wanted to specifically talk about the issue of the attacks and reasons to think that the official version of this specific event isn't correct he could have made a threat making an argument why the official story is wrong.

He didn't. He used it as an example for a larger class of events.

If he wanted to speak about the value in believing conspiracy theories he could have analysed a case like Princes Diana's death and the reasons for >0.01% believe that she was killed on purpose. The event happened years ago, so the evidence base is a lot better. There are interesting things to be said given how that case progressed. A case study that likely wouldn't use the term "real science".