Seriously I think the interface at the 14 is contacts for a generic switch. When you power the 14 on, there is appx 3 VDC across the two contact pads.
The switch can be implemented in the mount, by whatever e.g. using mercury, magnet, etc.
With the Wilcox J-Arm and bayonet G19 mount, the switch seems to be inertial and essentially driven by gravity. The switch is not in the lever, which simply re-orients the inertial switch with respect to gravity. You can demo this for yourself by attaching the 14 to the mount, power on, and then without moving the hinge, simply rotate 90º or so that the slider arm goes from horizontal to vertical: the 14 should switch off. If you listen you can hear the inertial part moving inside the bayo box. Obviously this design assumes a more-or-less upright head! But (IMO) is a good KISS solution. Your mount might be more sophisticated.
Sorry for my earlier, admittedly lame reply.