I think a lot of SIAI's "arrogance" is simply made up by people who have an instinctive alarm for "trying to accomplish goals beyond your social status" or "trying to be part of the sacred magisterium", etc., and who then invent data to fit the supposed pattern.

My thinking when I read this post went something along these lines but where you put "made up because" I put "actually consists of". That is, acting in a way that (the observer perceives) is beyond your station is a damn good first approximation at a practical definition of 'arrogance'. I would go as far as to say that if you weren't being arrogant you wouldn't be able to do you job. Please keep on being arrogant!

The above said, there are other behaviors that will provoke the label 'arrogant' which are not beneficial. For example:

• Acting like one is too good to have to update based on what other people say. You've commented before that high status can make you stupid. Being arrogant - acting in an exaggerated high status manner - certainly enhances this phenomon. As far as high status people go you aren't too bad along the "too arrogant to be able to comprehend what other people say" axis but "better than most high status people" isn't the bar you are aiming for.
• Acting oblivious to how people think of you isn't usually the optimal approach for people whose success (in, for example, saving the @#%ing world) depends on the perceptions of others (who give you the money).

When I saw Luke make this post I thought that ahh, Luke is taking his new role seriously and actively demonstrated that he is committed to being open to feedback and managing public perception. I expected both he and others from SingInst to actively resist the temptation to engage with the (requested!) criticism so as to avoid looking defensive and undermining the whole point of what he was attempting.

What was your reasoning when you decided to make this reply? Did you think to yourself "What's the existential-opportunity-maximising approach here? I know! I'm going to reply with aggressive defensiveness and cavalierly dismiss all those calling me arrogant as suffering bias because they are unable to accept how awesome we are!" Of course what you say is essentially correct yet saying it in this context strikes me as a tad naive. It's also (a behavior that will prompt people to think of you as) rather arrogant.

(As a tangent that I find at least mildly curious I've just gone and rather blatantly condescended to Eliezer Yudkowsky. Given that Eliezer is basically superior to me in every aspect (except, I've discovered, those abilities that are useful when doing Parkour) this is the very height of arrogance. But then in my case the very fate of the universe doesn't depend on what people think of me!)