Will, who knows a bit about psychiatry, frequently informs us that he has suffered from schizophrenia.

Makes allusions in that direction.

Paranoid schizophrenia (the most likely form because Will is high functioning) is incurable--although partial remissions often occur.

Incurable but fortunately treatable to a significant degree---especially the highly visible paranoid side of things. Unfortunately those with the negative symptoms are pretty much just screwed.

Will often posts in the obscure, mysterious fashion often typical of intelligent paranoid schizophrenics.

Absolutely.

(Essentially agree up to here.)

It is a mark of the ignorance of this community regarding psychiatry and psychology that posters seek to explain Will's ravings in terms of ordinary rational processes.

It is instead a mark of your ignorance of the community (and a certain degree of arrogant smugness) that you think that this position regarding Will's ranting can be remotely attributed to the community at large. Will's posting is for the most part not considered sane. (The community could also be ignorant about psychiatry but this isn't a mark of it.)