The problem here is that they've considered the entire world to be a war zone, with no time limits. It's a classic tyrannical move - declare an everlasting state of emergency that knows no bounds, and enforce the law as you choose within it.
If they're relying on war powers, there must be some limit to what is a war zone, or else their power to kill citizens on "executive finding" of past involvement with terror is unlimited.
If they're relying on anything else, the standards of self defense are much higher, and the wish washy principles in the paper have no legal foundation whatsoever.
To mock their criticism of water torture is entirely correct - instead of arresting and imprisoning without trial like Bush, Obama is asserting the power to kill. It's an outrage to the constitution, and an eerie first step taken by many tyrannical regimes in history.