Tanking with PLD can be a bit of a dance. Of course this person sounds like an idiot. But people seem to forget to watch the aggro meters, not just the tank. The DPS/Healers need to watch to see if their meter is climbing and not going down, that is the first clue to back off. The tank needs to keep an eye on the colors, if they start to change and you are losing hate the only thing a PLD can do to try to get it back is switch targets and go after the ones that are being lost.

The minute I see the color change I will switch up my target, so it becomes a dance. With people pulling aggro off of you it can get a but hectic in a large mob. All in all though its a group effort, people need to watch what they are doing and not just assume ( we all know what assume means) that the tank will hold aggro no matter what they do. Fights should go quickly, but as a DPS if you are constantly pulling aggro off the tank, maybe its something you are doing, and not the tank.