Correct. There are similar precautions in place for fuels (HERF) These are for certain types of fuel, like missile or torpedo fuel - not the low-grade jet fuel that is used in naval surface combatants.
I'm not a scientist either, but there is ZERO point ZERO percent chance that fuel around the ramp, be it in planes, fuel trucks or puddles on the ground, could be ignited by electromagnetic radiation from a cellphone.