I can say that this does work.
I have never got to the truth of why, but it does.
IE, inverter case is ground, ground pin on inverters 3 pin AC socket is connected to inverter case, hence ground.
PC cable ground pin is connected to PC case which is ground.
But with the ground pin on the plug connected it scares some inverters into fault mode.
Its weird, got to be a loop/impedence/standing wave issue, but damned if I can visualise how it happens.