Many of us have done thousands of these black night departures without an FD and fully coupled AP.
Anything practiced on a regular basis becomes second nature and a comfortable exercise. I used to fly single pilot IFR in an unstabilised Army Gazelle with no navaids for years. I have no doubt that the pilot on this particular flight was very competent flying the 139 day VFR. It is when we try to do something that is not practiced regularly that the holes start to line up. Add to that the (possibly) unfamiliar 2 crew operation, a night, overwater take-off plus induced pressure of a medical emergency (by non-SAR pilots) and it become far more hazardous.
Hopefully the FDR and CVR will clear up the mystery.