Agreed that during the proficiency check the CFIG would act as PIC.

Here is my reference as to why I think this is legal

https://www.faa.gov/licenses_certifi...ency_check.pdf

Specifically -





III. RECORD OF PILOT TIME.
There is no minimum pilot experience required by for the proficiency check. Enter only the pilot time that is acquired in an N-numbered aircraft. DO NOT ENTER TIME THAT IS ACQUIRED IN AN ULTRA LIGHT VEHICLE. If decimal points are used, be sure they are legible. You should fill in the blocks that apply and ignore the blocks that do not.