I wouldn't call Wayne a sicko survivalist. He sounds like 85% of the freepers. He just isn't being very bright by posting that stuff. It may not be that he made a big impression on the shooter, he just may be another red herring. Imagine how fast "Echelon" would cross reference this dude. Wayne has a disagreement with a cop and chose to write him this letter, nothing sinister, just a little too much bravado.
But, the Wayne who posted to the thread is probably the guy I linked to. From links on THIS Wayne Hicks' posts, it appears that DOC got his name from a group calling themselves "David's Outcasts". I'll put up a link in a sec...
I agree. And someone else having read the letter could have acted on it. IF, the letter comes into play.