Yeah I thought of that--my MX400Pro has a 2mm screw thru the hub and shaft, and the hub is slotted so it will compress a bit when the screw is tightened down. I replaced the stock bogus panhead screw it came with with a grade 5 socket head cap screw and elastic locknut. The MX400 has a one-way bearing and an autorotation collar on the bottom of the shaft and that's where it will shear in a crash, another bogus screw thru there.
Cant use that idea on the bcpp, the shaft is too small.

On the MicroHeli lower head that I put on my CX it had the same tiny setscrews, I took them out and used the stock Philips screws that held the old plastic head on. They fit and are easier to work with, I may try to use a pair of the same screws here.