I know you probably don't want anyone hand editing the /var/lib/PolicyKit-public/* files, but it is a quick and easy way to test things.
FYI : the parser can't tolerate a carriage return at the end of the line; e.g;
echo "yes:yes:yes" > foo.bar
vs.
echo -n "yes:yes:yes" > foo.bar
...it prints a "Out of Memory" error when running polkit-action from the command line, and things like the ACPI button shutdown stop working.
--- John