Wanted to let you know I liked the lesson on anthroplogy by Glenn. Oh and the other things on the episode ;-)
(And I can't understand how you are physically able to read this story while having a baby - I couldn't manage to do such things when my kids were babies, but then again I'm misophonic like Brandon, so I'm obviously just retroactively jealous.)
It took some perseverance, but after a while I got used to the language in this story. I think Moore indeed is very skilled in this. (You mentioned Joyce's Portrait - I haven't read that one, but I had to think about Ulysses when reading this - I really had to force myself reading that, even more than Moore's story, though Ulysses also had some great chapters where you really look at the raw stuff inside the head of the protagonist, just like in this story).
I also was surprised by the quote from Alan Moore. But because it's Moore, I doubt I should take his statement seriously. More so because my reading of the story (also before reading the introduction by Gaiman) was equal to yours: I thought the protagonist was mentally disabled, and I thought it was cool to think of such a point of view and to approach the language in an according way. But then again, other points in the story may indicate the opposite...
I'm interested in the fire motive of the book as a whole, so I hope that another chapter of Moore's book will be discussed on Elder Sign in the future.