My mental model of Eliezer Yudkowsky is that he thinks all postmodernism is nonsense - as others have noted. If he intended to say something equivalent to "Postmodernist got this point right" then what he wrote is not how I expect he would say it. Further, the attack that I am reading into his words is a standard understanding of postmodernism in this community.

But the community seems to agree with you more than I - so I'm adjusting slightly in favor of me misreading Eliezer's intent.