Huh, interesting. I wrote something very similar on my blog a while ago. (That was on cryonics, not existential risk reduction, and it goes on about cryonics specifically. But the point about rhetoric is much the same.)

Anyways, I agree. At the very least, some statements made by smart people (including Yudkowsky) have had the effect of increasing my blanket skepticism in some areas. On the other hand, such statements have me thinking more about the topics in question than I might have otherwise, so maybe that balances out. Then again, I'm more willing to wrestle with my skepticism than most, and I'm still probably a "mediocre rationalist" (to put it in Eliezer's terms).