Forgive me, but what a load of balderdash. Helmets are just not necessary on routine offshore tasks.
Safety is a compromise - despite whatever the "never over my dead body" experts say. Helmets would have been little use in most of those catastrophic incidents we have all read about. Basic airmanship and HUET training allow the remainder to escape.
Mitigation - spend the money on more sim / loft training and avoid the sudden / uncontrolled entry into water.