Jesus, those comments are very eye opening; there's a huge inferential distance even between LW/SIers and fellow futurologists. I hope there isn't a similar distance between futurologists and the general public.
The AMA may have received comments form curious people outside of r/futurology since there was an announcement for it on the front page. One thing about r/futurology, too, is that it recently tripled in size - only a few months ago it has around 6k subscribers. A lot of the growth came a week or two ago from a thread featured on r/bestof that got a lot of attention. Those things probably contributed to the inferential distance... If the AMA had happened a few months ago it may have been less, or indeed if it had happened a few months from now, counting on there being significant attrition of those new subscribers.
I'm sure most of us are used to just being able to badger him about things in the comments here on LW, but for anyone interested here's the link.