Have no problem removing my helmet when I am refuelling but then I am gorgeous and I want the world to see my glory...
(Seriously, as I said before when a similar thing was discussed, I can understand it can be intimidating for the cashier but have never heard about interupting fuel delivery as you were still wearing a helmet on the forecourt).
There is some basis for the static argument but depends on specific circumstances. Last week I watched a video from America of a guy filling up some steel and plastic containers whilst standing on the flatbed of his truck. Fuel vapours had collected in the flatbed, one of the containers discharged and WOOF!
(erm, he went up in a fireball, he wasn't barked at by a passing dog...)