We had the same nonsense with hard hats.
The plumbers wore hard hats but they were not issued to aircrew.
We couldn't wear a bone dome cause then we could not get our heads in awkward corners of the bomb bay.
We were not supposed to wear head dress on the flight line etc etc.
I always wore my forage cap; the amount of crud and stains on it were better there than on my head. I lost count the number of times it was knocked off. Being soft it protected my head but did not damage the aircraft. As my job did not entail running around with the engines running there was no fod hazard.
In fact wearing the original forage caps near aircraft did create a FOD hazard. The clip securing the eagle and crown could work loose and the badge drop off. There was a recall and the military tailors had to ensure the clips were bend back - there was no ban, initially, on wearing them near aircraft.
Although we took responsibility for our own safety it was the early ban on wearing helmets on the flight line that led to my hearing disability! H&S goes round and round like the b
y great wheel.