Whether 2 inches or 2 feet, the AHJ is making it up as he goes along. Perhaps he infers this from some other standard, pr he is allowing for a standard tub to be placed where an undersize one now sits - in any event, it's up to him to make his case.
The contractor, OTOH, has no need to justify his position. Absent a code citation, he's in compliance. It's up to the AHJ to show otherwise.
