It's a purely mechanical linkage. I've been trying to read the patent (US 5782436A). The USPTO has a new single-page web app. It's awful for finding by patent number, and worse when you want a full screen image of a drawing. It's clear that if one yoke is jammed and the other is moved with enough force, a spring loaded pin is forced out of a notch and the connection between the two yokes releases.

What's not clear is how the linkage still connects to the flight controls. The idea seems to be that the one which is moving wins. What is clear is that, if your side becomes disconnected, your yoke doesn't do anything. No wonder one pilot was frantic. It seems that you get reconnected by moving the disconnected yoke to agree with the one in control. Then the pin falls into the notch and the yokes are connected again. Not sure about that. You can see the pin and notch in the patent drawings.

This is independent of the fly-by-wire system. That's downstream from these mechanical devices.

I wonder if pilot training includes knowledge that yoke disconnection is possible.