Flaxton,
I am not interested in this becoming a hypothetical discussion where we construct suitable cases to suit our purposes.
This is training with Crew Members (as defined in JAR-OPS 3.988) - it is not CAT. Under your hypothesis all proficiency tests could be CAT as could Air Tests with Engineers on board. Under the auspices of JAR-OPS and ICAO Annex 6, there are no passengers on board - they are all Crew Members.
Jim