Worst gold bar abuse I've ever seen was the BAe PA31 ferry pilot from Warton who used to go into the mess at Boscombe Down in a blue sweater with four gold bars on his shoulder. Yes, I too mistook him for a Captain RN pilot until somebody quietly whispered in my ear to treat him like the bottom-of-the-ladder contract pilot he actually was.
I'm generally in the 'wearing bars unnecessarily is ludicrously pretentious' camp but your last sentence almost justifies it. Why treat him badly for being a contract pilot rather than a military officer?
Not even an air marshal or admiral outranks a civilian.