It was a legitimate question - do you have an ammendment that allows you to enforce a 7' rule for NM cable? Or it is simply a misapplication of the rules that you think you've been enforcing correctly?
As this is an NEC forum we don't want to confuse these young electricians you are referring to with made up rules or out of context rules.
The answer is yes. Refer to 411.5 (2008) as mentioned earlier as NM cabling is applicable to the feeding primary supply side for the secondary output. I believe California is still on the 2005 NEC adoptions, the Title 24 recent adoptions are parallel to the NEC 2008 in LV operating systems.
For those young electricians without the 2008 NFPA70, mentioned under [411.5(D)(2)&(3)] Secondary circuits "Conductors, cord, and cable of the listed system and installed not less than 2.1 m (7 ft) above the finished floor unless the system is specifically listed for a lower installation height." and..."(3) Wiring methods described in Chapter 3." In many cases the primary side is connected internally to the transformer barrier strip (Depending on type) along with the 12 or 24V output to the luminaire.
I hope this clears up an understanding of NM and exposed wiring that requires up to a minimum 7' height application. rbj