I made a fresh install of Unity and Archlinux (Unity-for-Arch unofficial repository). No problems there with the touchpad-settings: When I switch off the touchpad in system settings, it remains switched off after the next boot.
Then I made a fresh install on the same computer (Thinkpad T530) with Ubuntus Unity: When I switch off the touchpad in system settings, it will be reenabled after the next boot.
I made a fresh install of Unity and Archlinux (Unity-for-Arch unofficial repository). No problems there with the touchpad-settings: When I switch off the touchpad in system settings, it remains switched off after the next boot.
Then I made a fresh install on the same computer (Thinkpad T530) with Ubuntus Unity: When I switch off the touchpad in system settings, it will be reenabled after the next boot.