This one has been weighing on my mind. Essentially, I come back to don't intentionally operate in "high winds" if you don't have a rotor brake.
There have been numerous instances of helicopters that were shut down and still the NR turned up in storm winds, disastrously. Adding in the times I've waited, seemingly forever, for the blades to slow to brake application speeds, and the times I've prayed that the uncontrollable, randomly flapping blades would stop before they hit something expensive- and I don't think it's a good idea. There's no way to control the blades once they're to slow for aerodynamics.
Yes, you could get lucky once- or perhaps several times- by keeping the disk absolutely edge on to the wind, but the first random bounce will put your job on the line- will it hit something this time? It will eventually.
never worked for anybody cheap- I mean, more economical, than PHI- and 100% of their birds had rotor brakes. We routinely operated in 40 knot winds and occasionally even higher winds, and mishaps were rare- 1 a year, GOM wide, seemed to be a typical. Blade flapping can be hazardous, no matter how you're equipped.
If operating the helo is important, even with significant winds (greater than 15 knots, my estimation)- the proposed operation justifies the expense of a rotor brake.