That's not the point; I don't expect to be able to walk up to your front door with a random Yale key, jam it in and out a few times and have your lock reconfigured to accept my key instead of yours. That's what's happening here - it's not as sophisticated as a lock pick attack, nor as brute force as smashing the dashboard and shorting the appropriate wires.

It's a blind spot in the system that shouldn't exist if the car was locked. The OBD port simply shouldn't be physically connected if the doors are locked. A relay on the CAN bus pins trigged from the central locking might be a start.