The overhead of spawning the shell is going to be significant versus simply opening /sys/class/gpio/... directly.
The PIC attached via SPI sounds cool, though. It'd be cool if they supported USB-capable PICs and brought the USB pins out to a mini-B header in the final or second version of the Gertboard.
The person who wrote this probably didn't know of a different way of doing it.
still doesn't seem like a good example to set though.