See man mount. Are you under the impression that mount should not be allowed to mount a device as read only if the user chooses to do so and it must be read-write if the user has rights to the files? That would be rather foolish, as there are many good reasons that a user might want to mount a partition as read-only. That is what is happening here, because of the target user for Knoppix, Klaus has elected to default mounts of Microsoft partitions to read only, so that the novice just getting his first look at Linux with the Live CD does no harm. It is easy enough to change the access but it has to be done deliberately.