Bainbridge considers his position in light of his Catholic beliefs, and concludes that since the plotters are incapacitated now at Gitmo, there is no need to execute them according to John Paul II's teaching in Evangelium Vitae.
Interestingly, however, he concludes by noting "I confess that it’s a close case. The blood of thousands calls out for retributive justice." And he quotes in this respect another blogger: "The visceral reaction is to say that these men should die a slow, painful death. But I’ve got to wonder what that’s going to accomplish at this point."
Yet he shies away from this question of why it seems to be just to execute these killers. Why? John Paul II himself admitted
The primary purpose of the punishment which society inflicts is 'to redress the disorder caused by the offence'. Public authority must redress the violation of personal and social rights by imposing on the offender an adequate punishment for the crime....In other words the Pope recognized that for some 6,000 years, the traditional justification for capital punishment rested not primarily with the observation that its use will protect society, but rather that it is sometimes necessary to execute a murderer in order to restore the moral equilibrium upset by his offense; in other words, it is right for society to expect that there be a congruent satisfaction for the offense.
It is this just satisfaction for the offense that answers the natural reaction to the crime of murder in those whose sensibilities have not been blunted to this worst of crimes.
With respect to the 9/11 killers, the enormity of their offense has "overriden" the modern dissipation of this visceral hatred most people used to experience concerning murder.
There will always be cases so horrible, or in which there are so many victims, that the attempts to squelch our innate hatred of murder will be overriden, and it will be appear that the only just response from society is to exact the ultimate penalty from someone who, in a certain sense arrogating to himself a power belonging to God alone, dared to take another human person's life.