I think this would cause them to deteriorate more quickly. It seems to me the osmotic pressure would draw moisture out of the pearls and actually dry them out more.
Because they don't come from seawater. The pearl sac in which they form is bathed in a strong solution of hyaluronic acid (yup, the same stuff which snail facials feature, along with all the this-year face creams). I only discovered this after spending days working with salt water wet hands at a pearl farm and being surprised at no skin puckering or worse. Indeed my hands were silky smooth. It's the hyaluronic acid.
Pearls don't need remoisturising. Some pearls are centuries old and are just fine (see the crown about to be used in the coronation of Charles lll)
If sloshing on hyaluronic acid enhanced pearls I'm pretty sure that we would have heard at least whispers about it by now.