Feature request: make it possible to hide System Settings in menu

I use UbuntuMATE on public and staff desktops in public libraries, and I don't want users to be able to access the System Settings option from the menu in ayatana-indicator-session.  I can make the control center non-executable, but then I get an error message about it not being available.  It would be helpful to be able to hide it with dconf settings like many of the other items in that menu.
