The locking feature is misguided. There should absolutely be a mechanical interlock to prevent unplugging under load. But no key should be required to unplug a home charger, and no key should be needed to plug in a charger once the charge port is open. As I see it, the only security goals should be:
1. At a public charger, one should have to authenticate to _either_ the car or the charger to interrupt an active charging session.
2. When using a portable charger of the sort that is owned by the car’s owner, one should not be able to unplug the charger and thus steal it if one cannot authenticate to the car.
And that’s it. You should be able to unplug someone else from a public charger that can reach multiple parking spaces once it finishes charging.