Not in an aircraft who's RFM requires an additional person, I hope!  

If you are flying an aircraft where the NVG Supplement to the RFM requires at least one other person on goggles to operate below 300'AGL,or takeoff and land to unimproved areas, then they are part of a safety sensitive requirement, yes? 

Part 91 and 135 requires you to follow the RFM, placards, and OPSPECs.  For instance, in my aircraft's RFM supplement, there is a crewmember requirement (required crewmember) to operate to an unimproved site.  Required crewmember for a safety-related critical function, I would add!  To be a crewmember, you are more than a passenger!   To use NVGs, a crewmember must be TRAINED by the certificate holder.   

--quote--

RFM Supplement

Night Vision Imaging System (NVIS) Supplemental Lighting

Additional crewmember use of NVG during single pilot operations into and out of unimproved sites:

Landing:  Additional crewmember shall be equipped with and use NVG during the landing to assist in obstacle identification and clearing

Takeoff:  Additional crewmembers should use NVG during takeoff from unimproved sites to assist in obstacle identification and clearance, if operational considerations (i.e., patient status, etc) permit.

--unquote--

FAR 91.117 Alcohol and Drugs is a regulation for crewmembers, not just flight crewmembers.

Since the HNVGO to an unimproved landing demands a required crewmembrer shall be used in addition to the flight crewmember, and not should be used, it demonstrates clearly the crewmember is there to provide direct safety-sensitive function to the operation.