Is this still relevant? The alternative approach with listening to the D-Bus signal should be sufficient in most cases, and it may give greater flexibility as one may implement any complex logic around those events (for example, whether only admin-controlled settings are observed or the owner-user settings on an unenrolled device too).

I haven't heard anything about this in the year it was filed, but I think that the original reason for this (per the CL above) was to make it possible to start an Upstart job. I don't think that D-Bus signal helps there.