Which things are so important to EY that he feels it necessary to intervene directly and in a massively controversial way? By their actions we can conclude that the Basilisk is much more important to the LW leadership than e.g. the illegitimate downvoting that drove danerys away.

At the time the Basilisk episode happened Eliezer was a lot more active in general then when the illegitimate downvoting happened.

If you're saying that danger is an unavoidable cost of being able to generate interesting ideas, then the large number of other groups who seem to come up with interesting ideas without ideas that present a danger to them seems like a counterexample.

If you look at the self professed skeptic community there are episodes such as elevator gate.

If you go a bit further back and look at what Stalin did, I would call the ideas on which he acted dangerous.

The general population of atheists does not have problems with basilisks, and laughs them off when you describe them to them.

It's pretty easy to speak about a lot of topics in a way that the people you are talking to laugh and don't take the idea seriously. A bunch of that atheist population also treats their new atheism like a religion and closes itself from alternative ideas that sound weird. For practical purposes they are religious and do have a fence against taking new ideas seriously.