I believe this is a tempest in a teapot. It works both ways. I have diesel trucks and gas trucks and gas cars. Many times I find a car fueling with gas blocking the diesel pump for a few minutes. I also often find a diesel unit blocking the gas pump for, usually, much longer.
It does not upset me since I have often been on both sides. Many times it is because of the arrangement of the pumps, how busy the station is at that moment, and often because of convenience for each customer. I also believe that very few, if any, people block a pump deliberately. Usually the customer fueling with gas, especially a woman, has no idea that even diesel is different than any other fuel pump.
Anyone that gets upset about this would probably complain if a brand new rope was used to hang them.