The crew/passenger debate is a strange anomaly. It appears that it is allowed to continue in the system simply for the purposes of fudging the issue of police rostering.
Any objective assessment of what takes place in the aircraft would conclude that those on board are working together as a "crew" in order to achieve the mission. The precise division of responsibility is immaterial - the captain of the aircraft remains the captain, and the buck stops there.
In order to work to maximise both safety and efficiency, we use CRM - even PAOM 1 which classifies observers as "CAA-agreed passengers" requires annual combined CRM training for flight crew and observers because: " the successful resolution of aircraft emergencies requires effective coordination between flight crew and observers". It is no great surprise that this wording is somewhat similar to JAR-Ops 3 which states that "the successful resolution of aircraft emergencies requires effective coordination between flight and cabin crew"
Observers are seen as equally important in CRM terms as cabin crew are for airlines. This is why we need to select people to do the job who we can work with, and who will be an asset rather than a hindrance in terms of achieving the mission. The organization needs to have confidence in its training staff to pick those people. If it doesnt trust their judgement, it needs to change the training staff.
Shall I get off my soap box now?