Ok, called a friend who was consulting in this. He got out of it due to NADCAP. Did I already mention my

?
Hopefully you have the latest Revision D.
2750 is a how-to specification on pyrometry. It does not specify the processes requiring the survey/pyrometry specs. However....
As I mentioned previously, your customer (Boeing?) may have a specification for your process that calls out 2750. The NADCAP auditor should be citing the specific process specification, not AMS 2750. If the specific process calls out 2750, then you will probably have to do a survey. Hopefully, it will just be an initial survey only; especially if you have sufficient monitoring equipment.
Also, if it's fuel cell coatings/ other processes, you may have additional requirements like Temp/RH monitoring, and increased recording of refrigerators/freezers.