They had a chatroom on his irc server. They also had chatrooms on efnet, 2600, anonops, and rizon. So to claim he's a big part of the organization is pretty disingenuous. Of course, the question remains whether the authorities are being deliberately dishonest, or if they actually think he's a "leading figure" in LulzSec. I'm not sure which outcome would be more depressing, although I suppose I'd take an incompetent government over an evil one any day.