--color does not work

If I understand correctly, we're supposed to give either --grayscale or --color as arguments

  --grayscale           Convert images to grayscale (default: True)
  --color               Use color images (default: True)

but when using --color the images are converted to grayscale anyway, and I don't understand how the arguments parser is supposed to work here

    group = parser.add_mutually_exclusive_group(required=False)
    group.add_argument(
        "--grayscale", action="store_true", help="Convert images to grayscale"
    )
    group.add_argument("--color", action="store_false", help="Use color images")
    parser.set_defaults(grayscale=True)

because later it's just grayscale=args.grayscale and args.color is never used and grayscale is set to True by default ?