Update : now that i think about it your probably parsing the ~file to see the hildon default? If so we can package together an unused defaults.list (with all maemo apps as defaults) for reference and hide it in /usr/lib/dbus-switchboard for you to use intead of ~ files since my current implementation of those ~ files is not reliable enough to use anymore (useless if you install/upgrade more than once on any given os flash)
About sudoers : My first though was separate registration into separate .py file whose sole purpose is to update the defaults.list, but now that i see your gui i think it might be better to sudo the entire dbus-switchboard-gui python file and run the whole program as root... thats less of a hole than leaving capability to copy arbitratry file and overwrite defaults.list as 'user'... less important because its a tablet, but probably more acceptable to long time linux users. Sudo on the gui at least the user sees what hes about to do rather than it getting overwritten as a blip in someone elses ui-less script to cp that file.