The touch ID thing was weird from what I read, why can Apple replace a button safely but someone else can't, one issue was that Apple refuses to sell the genuim

The touch ID thing was weird from what I read, why can Apple replace a button safely but someone else can't, one issue was that Apple refuses to sell the genuime part, for security reasons can't you reset the touch ID stored data and have the user use his PIN after the replacement is done(in the assumption Apple wold sell you the button )?