technically your hair past the scalp is dead already on your head... so i really dont see much difference when its off the head...
that being said, i doubt id want to use it for stuffing though, hair tends to be itchy, and thin random stray hairs will poke out of fabric..
besides, once its off the body, the follicles producing oil wont be attached either... so not sure how it would still work after its been washed