Here's a simple answer.
Just ask the instructor concerned to explain why it is a tech rig. Ask him to point out the specific reasons why it is for technical diving. Ask him also to point out what exactly makes it unsuitable for recreational diving.
Finally, ask him to provide the NAUI kit list for the course/s that you would assist on.
It's easy for instructors to speakauthoritively, but more difficult for them to speak insightfully. Some instructors like to use throwaway comments (i.e. "it's a tech rig"), but ignorance is exposed when ask to explain those comments.
At the end-of-the-day, it's his school and his class; so he can make the rules. That said, what benefits do you feel that you have to gain from assisting a 'mentor' who, as a scuba professional, obviously has some major knowledge gaps, poor breadth of experience of the wider scuba industry/community and a very narrow-minded attitude? To leap even further in assumption; his unwillingness to explore the added teaching benefits of different kit configurations might mark him out as being a scuba educator who prefers to run classes at the bare minimum of effort and motivation.
Just saying.........
Oh, just for the record - taught a PADI PPB class today, using doubles, long hose and necklace AAS. Student got to try out force fins, jet fins and split fins. Dropped his weight belt from 5kg to 2lbs. Worked towards a 'balanced rig' and confirmed his ability to swim the rig with no air. Got horizontal trim cracked and looked at buoyancy requirements/distribution of individual kit components when he buys stuff at a later date (not from me). He got to try necklace AAS - and showed him how to make his own for $2. 3 dives, rather than 2. Video'd his practices for review and feedback tomorrow. In a single day, we had progressed to horizontal ascent/descent, helicopter turns and non-silting fin techniques.
Yep... there's no excuse for 'bare minimum' instructors....
