Well, it is good in general to caution flyers about putting wrong type of fuel into aircraft, BUT…
What is the other fuel being dispensed at that airport?
Putting kerosene into a piston-engined airplane may be fatal. (Aviation kerosene - JetA.)
Most helicopters have turbine engines, perhaps fewer of them at a small airport where R22s and such may operate.
Mis-fuelling of similar looking aircraft might occur, I’d especially watch R44 vs R46 helicopters. Large placards needed. (I’m not up on nozzle-socket sizes.)
But if the airport in question here provided only 100LL avgas and is adding G100UL avgas is NATA’s message worthwhile? If not it should be addressing airports where there is a mix of octanes and fundamental types of fuel.