Well, if the defense can make a case that CW is boarderline MR, or Autistic, which seems unlikely to me, the higher level thought process of making a phone call rather than immediate physical reaction was beyond CW in the moment. Perhaps he was on some medication that clouded memory, so he was relying on the hypothalamus, which would work on emotional responses. Perhaps he has a brain lesion, that blocked higher levels of functioning. A phone call, is abstract, one removed from concrete behavior/intervention, actively choking someone. If CW had some sort of TBI, brain damage, that could explain and possibly justify the flawed thinking he displayed in a situation of high stress.
Structure and Function of the Brain | Boundless Psychology