You're making some good points. Unfortunately, shminux is often just that easy to pattern-match with "naive postmodernist" stereotypes, which doesn't help for charitable interpretation.

In my experience, his points are usually more coherent than this (or, in most cases, more coherent than an average interpretation of his posts' contents would suggest).

The charitable interpretation is that shminux always implies in his points something similar to Eliezer's notions that you can't just step outside of your own perceptions to see the territory directly, but do have some mechanisms already in place that receive "new" information from somewhere which you have no control over, which is what (AFAICT) shminux calls "reality".

Basically, AFAICT, shminux draws the boundaries for the term/concept "reality" in a slightly different area/manner, one that allows him to remove the node "external territory" entirely without sacrificing practical points like "believing I can fly doesn't prevent me from going splat if I jump off a building". The utility of this difference is apparently obvious to him, and debated by others.