The Mouse & Touchpad settings panel has a new On / Off switch for the touchpad. I toggled this on a laptop, which had no other input device connected, and the touchpad was happily turned off. From here, I needed to clumsily navigate with the keyboard in order to turn the touchpad back on. Keyboard navigation with the tab key is not at all intuitive for most users, and disabling the touchpad sticks for the user account, so this could easily be sufficient to "break the computer."

This settings panel is aware that the touchpad is the only input device connected, so it should really produce some kind of sanity check when the user disables it. A modal dialog with a countdown would probably make the most sense.