Comment 6 for bug 50209

Matthew, the functionality doesn't belong in the Users and Groups account properties. It belongs on the system level, or the control level. An ordinary user with the same privileges as the logged in user would not have the ability to power down the system. It's something GNOME is doing via its connection to dbus, I think. What GNOME should be doing is allowing you to limit what options are offered by default. There's no reason a user logging out should be offered a painter's palette of logout buttons, when a single logout/cancel button would suffice. If they need to shut the system down, they already would know how.

If you put the functionality as a users/groups attribute, someone with an installation like mine would have to adjust those properties or group memberships for upwards of 45000 users. Not an option. If GNOME has added this option, they should offer some functionality in turning it back off again.