I would never call GC a jerk, but it's clear to see what he means -- sending out information via official posts on the forum is something Blizzard has done for a long time, and it's really a bad way to go about it. To their credit, they've been trying lots of new things lately, from official interviews to class Q&As and just plain releasing official information on the site. But I've always thought (and still think) that the company could use an official blog -- back when I was playing Dark Age of Camelot, I really enjoyed all of their work on the Camelot Herald, and I think Blizzard would benefit from something more like that. They do have a section for official news on the front page, but that's mostly licensed items and marketing information, not actual updates to the game.
In the meantime, we'll keep getting hints and scraps from the forum. It's probably a bit much for GC to ask that some of his posts not be talked about at all -- if he was on Twitter, every tweet would be pored over, too ("GC had pancakes for breakfast, nerf pancakes!"). But I do think that if there was more information coming from official channels about class balance and changes, the forum posts wouldn't be such a big deal.
Update: The folks over at Wowraid tell us their bluetracker doesn't track posts with "[Not tracked]" added to them. But doesn't it show just how silly the whole forums thing is that we have to have webpages that track forum posts by the blues, and then they have to have flags in those posts that keep us from tracking them?