This could be a hoax. WD40 contains volatile components and flows easily. The oil film it leaves on curved surfaces is very thin. I had a discussion with a chemist on Brit Iron some years ago. He pointed out that all lube oils will decompose as time goes by, creating corrosive components. So, even a thick oil film may create acids if left to oxidise.
Best protection is dry storage under vacuum; Next best method is encapsulating the item in resin, similar to what nature does.
Alpha Bearings used to protect their big end bearings in resin. If left in original packing, these bearings will be as good as new for 50 years or more.