We cannot have it both ways.....the TFO are part of the "Crew" or they are not.....which is it?
If they are not part of the "Crew" with duties and responsibilities that inclusion affords....then CRM does not apply to them beyond the Pilot informing them of on-going situations and directing their actions re pending Emergency Landings, etc.
If they are "Crew"....then CRM, duties and responsibilities along with liability follows that inclusion.
The fact the ANO and FAA rules say one thing.....and the reality of the situation is another has no direct bearing on how things work in the aircraft. The Reality is the "Crew" works as a team....and in essence works as a "Crew"....one Pilot and two TFO's, or a Pilot and two Medical Personnel....but it is a "Crew" Operation in practical terms.