Setting the policy to True displays the accessibility options in the system tray menu. If you set the policy to False, the options don't appear in the menu.
If you set the policy, users can't change it. If not set, accessibility options don't appear in the menu, but users can make them appear through the Settings page.
If you turn on accessibility features by other means (for example, by key combination), accessibility options always appear in the system tray menu.