Sorry, totally bad advice. I threw a prop on my very first run of my brand new OS 62 FS. Besides, How is it bad? I double nut engine mount bolts too. Is it crazy unneeded? My first flight the engine bolts loosened and the freakin engine fell right off! Hanging there by the throttle cable for a dead stick landing. IF it fell all the way off the center of gravity would be blown and amount to pile of sticks!
Anyone in this hobby knows to be double careful and sure. At least the ones with experience.
If there is no need for a safety nut, Why does OS include one with a new engine? Boom!