MD600,
That's really down to who constitutes "ground crew" and who is a "passenger", in the true meaning of the definitions. Those of us in the profession know this has regularly been exploited, as a perceived loophole in the Permit to Fly for the Gazelle.
So, were these 'passengers' or 'groundcrew' prior to the flight?
Read the CAA's own definition of 'ground crew' given in the report, page 59, lined box, top right. Were the other two occupants "engineering staff required for the maintenance of the aircraft away from base"?
Was their attendance required for the 25 hour inspection, or could it have been carried out without their presence?
If not, both were passengers on the flight and should not have been carried. The report stated that neither passenger had any engineering qualifications in this respect. I noted that the term "passenger" was used, not "ground crew", for both of them.
We used to move Gazelles around with only two people, btw. One to steer whilst holding the tail, the other to push on a rear skid tube. Including this particular aircraft when it was still XW898, in it's previous, RAF use.