If you want to avoid guild drama - usually the smartest course of action - tell them to stop relying on their mods and just use their brains instead. I would recommend using Quartz for cast times, since it's much more reliable than the default castbars.
Regardless of what you do, the best solution is to drop dead weight in your raids. For 25 mans, maybe you do need to drag them along so they can get their free loot, but with WotLK changing the standard to either 25-man or 10-man for any raid, people that aren't pulling their weight around are apt to get dropped in a hurry, regardless of class/spec.
What position they have in the guild should be irrelevant in terms of who gets spots into raids and who doesn't - until you've got it on farm status, the best performers are the ones that get the raid slots, whether they're a raw recruit or a guild founder.