In our office, we have a whole bunch of Magic Keyboards, and for various reasons too complex to go into here we have a habit of moving them around and connecting them to different Macbooks. As soon as they are connecting with a Lightning cable, they will typically auto-pair with the machine via Bluetooth, meaning that even once the cable is removed, they continue to be connected. It's both annoying (and potentially even a minor security risk) for someone else to have access via a keyboard they just pick up.
We can't return the Magic Keyboards; is there a way to either disable their Bluetooth behaviour or prevent the machine from auto-pairing, so they only work over USB?