It appears that the military legal establishment, which includes experts with years of study of not just the text of the various conventions (don't forget the Hague Convention!) on treatment of prisoners and noncombatants but the military context, was completely excluded from the drafting and decision process. This is not the first time we've seen this in this administration; or, for that matter, in any previous administration since the beginning of the Cold War. If there is one thing that we should all have learned over the nearly four centuries since Gustavus Adolphus established the modern court-martial, it is that military law is meaningless when not in context. Regardless of any abstract attraction of Yoo's position, it is curiously contextless. It reflects only the abstract policy concerns of this administration. (It is also bad rhetoric in that it pays insufficient attention to alternative theories and courses of action, which is not appropriate in a document provided for the purpose of advising political decisionmakers.) It does not make a satisfactory effort to encompass the context of current interpretations of international law, such as the Balkan situation of the 1990s; of the history of US/Persian Gulf/Islamic/Arabic relations; or, most critically, of the history of US armed forces in asymmetric warfare (which is spotty at best).
Functionally, this is nothing more than the old technique of dehumanizing the opponent to justify extreme measures against him or her. Leaving aside the disreputable history of the technique, it is just plain bad strategy when attempting to employ military forces. There are certainly flaws in the "law professor letter;" but at least the policies it implies are not inherently counterproductive. If there is a "suicide pact" in this disgusting mess, it is the Yoo memorandum (or at least the policies it supports). Suicide is something one does to oneself. Failing to use all defenses may be exceptionally dangerous; but it is not suicide.
Update: Phil Carter's comments, although perhaps not so disdaining of the DoJ's position, indicate that I'm not the only officer who later went to law school who questions both the constitutionality and the wisdom of this administration's approach to interrogating alleged terrorists.