@ Jojoe I don’t think the Ohme does secure the cable. However, if one end is secure to your car it’s unlikely someone is going to try cutting the cable whilst it may be charging!!
The only issue with the anchor you posted is the security of the fixing screws. Masterlock supply steel ball bearings which can be hammered into the Allen head screw fixings to make them much harder to remove!!
Have you tried searching for ‘Ground Anchors’ on Amazon?