...but the logic they use to rule suicide bombing as permitted is rooted in the Islamic principle that necessity overrides prohibition.
Well, you're allowed to eat pork if your starving to death, but thats only if you're about to die. The principle of "necessity overrides prohibition" only applies in that kind of situation. Suicide is haraam & if you can show me anywhere in Islamic history where it was used in war I will buy the necessity doctrine. It simply does not exist & what these people are doing is totally against Islam, and that too in killing other muslims.