@Stephen
Thank you for that new information. I wasn't aware the basic operating system was a Linux derivative. I thought Canon had a proprietary operating system: DRYOS. Granted, you would want to hide or protect some of the core functionality like the boot record of the operating system. But I don't think that the core operating system is on the SD card, it is most likely in internal Non-volatile or RAM memory. That is something you can protect through administrative privileges'. So, if the operating system is not on the SD card, why would you need to protect the root of the SD card?
...and furthermore, you can even format and access (read/write) the root of the card when it isn't in the camera. Again, I'd be really surprised to find that the root of the SD card held operating system files you could corrupt. If you can write the .fir file to the root of the SD card when it is in a card reader, why shouldn't you be able to do same in camera (i.e. write to the camera mounted SD card - but certainly not to non-volatile memory)? What am I missing?
