He interviews various casual raid guild leaders in his piece. These are guild leaders who, back in Burning Crusade, mostly ran Karazhan and maybe dabbled a bit in Zul'aman. They certainly were far behind the curve. But they had a dedicated core of 10 raiders who got together, faced the challenges, and overcame them. But now, even these casuals are saying that the end-game is just too easy.
One guild leader interviewed is finding that some of their raiders have gotten all the loot they need from Naxxramas and maxed out Northrend Achievements and Reputations, and, for lack of anything to do, are not logging on for days or simply letting their subscriptions lapse altogether, leaving their guild leader to make the painful decision once Ulduar comes to either refuse to give them their raid slots back or kick out their replacements.