Former Secretary of State Donald Rumsfeld's memoir is another example of Republicans using their political success in blocking changes in national-security policy as a vindication of those policies on the merits:
He remains unrepentant about the Pentagon's overall handling of detainee interrogations, his own approval of interrogation techniques that were harsher than those in the Army Field Manual, the management of the Guantanamo Bay detention facility and the creation of military commissions. And he notes that even the Obama administration has found little recourse but to maintain the Guantanamo prison and continue holding suspected terrorists without according them prisoner-of-war status.
There's a distinct difference between policies the Obama administration adopted voluntarily -- indefinite detention, the two-tier system for trying terrorism suspects that includes military commissions -- and the policies Congress actively prevented the administration from changing. The ongoing existence of Guantanamo Bay isn't vindication of its necessity as an institution; it's an example of Republicans successfully leveraging hysteria over terrorism into a political victory. But even the Bush-era policies the Obama administration maintained on its own don't prove those policies were effective on the merits. Obama's continuity with Bush is also continuity with Bush policy after the Supreme Court got finished altering it, not Bush policy as it was originally envisioned.
Tellingly, Rumsfeld says that he "regrets not leaving office in May 2004 after the disclosure of the Abu Ghraib prison scandal." But as the above paragraph shows, Rumsfeld doesn't actually regret any of the actual actions that led to the Abu Ghraib prison scandal, like his approval of torturous interrogation techniques.
In saying so, Rumsfeld at least provides a sort of intellectual honesty lacking in his boss. President George W. Bush said in interviews after his memoir was published that he was "sick to his stomach" by the pictures from Abu Ghraib but later defended the use of waterboarding.
The interrogation techniques used at Abu Ghraib, however, had "migrated" from Guantanamo Bay after being approved by Rumsfeld. So it doesn't actually make sense that they would make Bush "sick," any more sense than it made for him to insist the United States doesn't torture after his administration had approved the use of torture.
So when Rumsfeld says he should have resigned because of the scandal, not because of the torture, well at least he's being consistent.