By all means check out the arguments, but argument doesn't screen off authority, for roughly the reasons Robin Hanson mentions in that thread. Few human beings ever have verbalizable access to all their evidence, and you would be a fool not to take expertise into account so far as you can determine it, even for unusually well-documented arguments. I encourage you to keep scrutinizing EY's track record - and those of any other contributors you often read. (BTW I upvoted VN's comment, to help ever so slightly in this endeavor.)
Few human beings ever have verbalizable access to all their evidence,
This being the case it indicates that the authority is screened of imperfectly, to the degree that the arguments are presented. For example if the arguments presented by the authority are flawed the degree of trust in their authority is drastically reduced. After all part of the information represented by the awareness of their authority is the expectation that their thinking wouldn't be terrible when they tried to express it. That turned out to be false so the earlier assumption must be discarded.
I blew through all of MoR in about 48 hours, and in an attempt to learn more about the science and philosophy that Harry espouses, I've been reading the sequences and Eliezer's posts on Less Wrong. Eliezer has written extensively about AI, rationality, quantum physics, singularity research, etc. I have a question: how correct has he been? Has his interpretation of quantum physics predicted any subsequently-observed phenomena? Has his understanding of cognitive science and technology allowed him to successfully anticipate the progress of AI research, or has he made any significant advances himself? Is he on the record predicting anything, either right or wrong?
Why is this important: when I read something written by Paul Krugman, I know that he has a Nobel Prize in economics, and I know that he has the best track record of any top pundit in the US in terms of making accurate predictions. Meanwhile, I know that Thomas Friedman is an idiot. Based on this track record, I believe things written by Krugman much more than I believe things written by Friedman. But if I hadn't read Friedman's writing from 2002-2006, then I wouldn't know how terribly wrong he has been, and I would be too credulous about his claims.
Similarly, reading Mike Darwin's predictions about the future of medicine was very enlightening. He was wrong about nearly everything. So now I know to distrust claims that he makes about the pace or extent of subsequent medical research.
Has Eliezer offered anything falsifiable, or put his reputation on the line in any way? "If X and Y don't happen by Z, then I have vastly overestimated the pace of AI research, or I don't understand quantum physics as well as I think I do," etc etc.