The chargeport cover is not locked when the vehicle is locked
Even when the vehicle is locked and charging you can stop the charge using the button and remove the charge cable from the Type 2 socket. On public chargers this will also unlock the end connected to the charger and hence make it possible to steal the charging cable, not to mention stopping the charge.
Seems to me that there is little one can do to prevent some malicious person stopping charge on a public charger or nicking the cable.
Are you sure about this? I thought that you could not disconnect the charging cable if the car was locked, even by pressing the button next to the connector on the car.
Even when the vehicle is locked and charging you can stop the charge using the button and remove the charge cable from the Type 2 socket. On public chargers this will also unlock the end connected to the charger and hence make it possible to steal the charging cable,