Can an inspector require a specific grounding technique?
If you are taking training this can be found in the NEC section 90.4 "Enforcement" the second sentence states he is the legal jurisdiction having authority for the enforcement of the code and he has the responsibility for making interpretations of the rules, ...

So in answer to your question yes.

The only thing you could do is to appeal it to his employer (the city council or whomever) or try and reason with him. Personally I wouldn't try and tick him off.