Maybe they should have tried that Hexis Wrap material. That has some serious stretch potential. Plus, you'd think they'd have the bottom of the barrel heated with like an infrared heater to evenly heat the material. That way you could just plunge dip the helmet instead of forcing it like that with uneven heating from the backside.
Come to think of it, you probably could use a thermoforming machine and actually be able to pull this off.