Surely, if he has a B2 licence here and CASA gets their act together and swaps to the 100.66, then he would get a CASA B2. Problem solved.
if thats the case then the CASA B2 would cover the same scope as the one here thus no problem. if this is not the case then the EASA CASA harmonization is not such!
For info, here in EASA land, a B1 or B2 can sign for electrics from the Gen to the Busbar. a B1 can sign for any electrical going from Busbar to MECHANICAL systems or avionic systems that DO NOT require test equipment to prove the function. a B2 can sign for Electrics from Busbar to all avionic equipment.