Is a psychologist part of every accident investigation team?
Or is the nature of AF447 unique enough to warrant it... Were they used on the TWA800 recovery vessels?
I don't downplay the potentially gruesome nature of the accident scene, but am sure most large accidents are gruesome, by nature, to the untrained.
The ship may have several crew members untrained in dealing with mass trauma scenes, so a psychologist may be useful and appropriate.