Aaarrrrrggggghhhh. Sorry guys, I forgot a step! In case I need to find this process again in the future, follow the following! Note for anyone else; this works for me. If you try it as well, test it first on an image you dont mind screwing up.
Select image in Aperture. Click on File then Relocate Original. Put image(s) in a folder on your Desktop. In the terminal paste the following
exiftool -overwrite_original_in_place -preserve "-Copyright=" /mydirectorypath
Instead of typing the directory path you can drag the folder on your desktop that contains the image(s) into the terminal. Hit enter. If succesful it will say image files updated.
Go back into Aperture. On the same image click on File, then Consolidate Original. Select Move (not Copy) in the pop up screen. Then right hand click on the image and select Update From Original.