I believe the biggest problem they have with Kira is that he was SUPPOSED to be the Ultimate Coordinator, the one who could use his power to guide/control the otherwise retarded masses that are the human race. Instead Kira goes through life as a civilian, gets stuck up in Lacus Clyne's No-Killing BS and then retires to a remote island at the end of SEED. I'd imagine Dullindal thinks he has skipped out on his responsibility...

As for Rey.... I don't know.... He said he wanted to fight so that there would never be people like him or Shinn, the super-killers if you will, and thats why he'd rather wipe people's brains with Destiny Plan. I also believe he shares Dullindal's sentiments about Kira not playing a bigger role in guiding humanity, seeing as how Rey will die shortly and wants Shinn to be the Ultimate Coordinator Arbiter/Controller that Kira could have been.

He also probably hates Kira because Kira and the Lacus Faction just seem content to stop the battles in the here-and-now, and don't seem to have any bigger plans for preventing further wars in the future.

Or I might be totally wrong....