Of course possessing a filesystem of another kind makes the device "not a device". After a few seconds on the command line the problem went away:
$ sudo pacman -S dosfstools $ sudo mkfs.vfat -n BILLY /dev/sdb1but the sadness remained. At l(e)ast I can listen to some badvoltage while driving.
Oh yes, did I mention it doesn't accept any format except mp3? And how does it signal it? By not showing the files at all, of course.