That is an excellent question.
Basically, I think it does need both, but I don't think you need GFCI, GFP would suffice (but code is changing a lot on this and I haven't been keeping up with the changes for some time now.
I have used a 2-pole contactor that would act like a switched neutral (both hot and neutral run through the contactor and the contactor coil gets energized from the breaker, so power on = contactor energized, power off = contactor de energized). So, you could use a GFP breaker feeding through a contactor (both hot and neutral) to feed the gas dispenser and I believe that meets all the intent of the code.
