Funfly
As a fixed wing pilot of very limited experience but a lot of theoretical knowledge, I have found this forum to be most informative about helicopter operation and hazards. Perhaps it would be technically possible to design a rotor head that would allow the blades to be angled sufficiently to unstall a stalled rotor disk given sufficient height. I don't think it would have helped in this particular incident. Perhaps a 'one shot' system with a small rocket fitted at the tip of each rotor could be used to bring a stalled main rotor back up to speed? The system need not be complex or heavy and the added rotor inertia could be advantageous. Not sure that health and safety would approve.