Unity device blacklist nonfunctional

Installing 14.04 in a classroom dual-boot environment, Unity shows icons for the Windows partitions on the launcher, nonfunctional since they require root to mount. Such extraneous icons only serve to confuse the user.

Googling, I found out about the com.canonical.Unity.Devices blacklist gsettings entry. I made a script that generates a schema such as this, for internal drives:

[com.canonical.Unity.Devices]
blacklist=['F236BFEF36BFB349','1A98C11998C0F473','c251a534-47dd-4ecb-a62c-2ced6914ef4a','122357ec-3130-482f-b20e-a4c6522e0873']

Here's the corresponding output of blkid -o list
device fs_type label mount point UUID
-----------------------------------------------------------------------------------
/dev/sda1 ntfs System (not mounted) F236BFEF36BFB349
/dev/sda2 ntfs OSDisk (not mounted) 1A98C11998C0F473
/dev/sda3 swap <swap> c251a534-47dd-4ecb-a62c-2ced6914ef4a
/dev/sda4 ext4 / 122357ec-3130-482f-b20e-a4c6522e0873

I put the file in /usr/share/glib-2.0/schemas and ran glib-compile-schemas on it. The entry _does_ show up in a user's session as evidenced by gsettings get and dconf-editor. dconf-editor also has a documentation line for the entry that indicates that this _should_ indeed prevent the named drives from appearing.

However, the icons persist in appearing, even on a clean home directory (no old user configuration to confuse anything).

Can this be fixed, or is there another way to prevent Unity from showing local internal drives to users who have no means of accessing them? Disabling drive icons altogether would be suboptimal but perhaps workable too, though it'd be preferable that the removable drives would get icons. However, even removing unity://devices from com.canonical.Unity.Launcher favorites didn't prevent the icons from appearing (though the same edit did succeed in removing other application icons, so the setting itself went through properly).

lsb_release -rd is:
Description: Ubuntu 14.04.1 LTS
Release: 14.04