Ralph: Nanny state means nanny compromises.
The chances of being flash burnt in a post accident crash are slim to nil.
The chances of exposing unnecessary flesh to the chemicals/heat of working around the helo - slim to nil.
Common sense should prevail and the overiding factor is comfortable surroundings whilst flying, taking safety into account.
PS: Bear in mind that the moment your flying overalls are washed/dry cleaned - means the end to the flash protection it previously provided.