This is the landscape of NGRI the defense (not guilty by reason of insanity or incompetent to be executed). Or lack thereof.
If nothing else, this open declaration by a forensic expert reveals a rationale of the “greater good” somehow strengthens him even when other experts disagree. This includes one particular death penalty case. He stands by his belief in the legal concept “reasonable medical certainty.” Not a few legal commentators wonder what that phrase actually means when a qualified expert opines this as an underlying source of reliability for the courts. He does mention some ethical guidelines of his profession. Whatever works for him, I guess.