I can assure you that BPI certified analysts do NOT care, at all, what home inspectors do. The requirements (not optional) for gas detection and CO monitoring is limited to energy auditing. I, personally, have decided to make it a part of my home inspections as well. I really don’t care if anyone else does it or not.
For those who do, I recommend that they not record the absence of gas or CO … but limit their remarks to instances in which it is detected.