Fails to load and start games from WBFS if container is read-only

I am not sure if this is an error of d2x-cios or of the USB loader.

If WBFS files on an external hard drive with FAT32 are marked as read-only in the file attributes, the start-up fails and the Wii restarts. It is my understanding that WBFS files are not written. Why then are they opened for writing? 