I don't know the ins and outs of the CDM shooting, only the bits I saw on the news but my opinion is that the officers who shot him (who just like the pilots had to refer back to a command post for authorisation first) acted correctly based on the information they had. The problem with that case is that the information the officers were given was crap. If they'd have had good intelligence he wouldn't have been shot, but the right person probably would have.
Now to try and tie the two situations a little better for comparison, if CDM had been a suicide bomber and by shooting him they stopped him detonating the bomb that would have been a good thing. So now what happens if someone comes over to his body and starts moving him? Here it becomes different to the Iraq video because the police, unlike the pilots, would have been in direct threat of someone else trying to set off the bomb. If someone had tried to grab the trigger the police would have been close enough to physically restrain them from getting close enough without slotting them, something the pilots couldn't do.
Isn't it nice that everyone has 20:20 hindsight.