If PackageKit is indeed lacking functionality to handle 3rd party updates (i.e. there is no fix that doesn't involves a big load of work), maybe an easy fix could be to gray out the "show available upgrades when backend provides them" option in the updater if the PackageKit plugin is selected. This way non-working functionality wouldn't be advertised to the user. PackageKit doesn't support package upgrades. That's the reason why the updater applet cannot show them. You are right, the settings dialog should gray out
https://bugzilla.novell.com/show_bug.cgi?id=461647
User tgoettlicher@novell.com added comment
https://bugzilla.novell.com/show_bug.cgi?id=461647#c4
Thomas Göttlicher