if you have salt and pepper hair and the back of your hair is still relatively black with most of the sides, top, and front salt and pepper, what happens when you transplant the hair in the back to the front and top? does it also eventually turn grey also?
Whatever hair is in the back (donor area) will be the hair in the transplanted area. Over the many years of transplanting hair (20+ years), I have not seen any dramatic changes in hair color for patients with grey hair on top and darker hair on the back. It seem to generally blend in well.
In other words, hair color does not usually change to another color just because it is transplanted. In your case, the hair might turn grey after it is moved simply because it would’ve turned grey even if it had not been transplanted.