When you pay for a charge the plug locks into your you car and cannot be removed until the charge is completed.
I looked up GeniePoint and they are a pay to use charger.
https://www.drivingelectric.com/your-questions-answered/1208/complete-guide-to-the-geniepoint-charging-network
If you are not sure if a car is still charging you can tug on the handle, it will not come out.
Therefore, Mr EV would not be able to unplug the other car unless it was done charging.
The owner of the other car must be new to this.
There is a EV charging area here where I live that is free, what annoyed me is that there are 6 Tesla spots and 4 spots for everyone else.
It annoys me when I come up and the Tesla spots are mostly empty but a Tesla decided to take up a non Tesla spot. They have an adapter (I can probably get a Tesla to regular EV adapter never bothered) most do not.
Then the other EV owners have to jockey. Those chargers are free and can be unplugged from a car and plugged into another, they do not lock.
I used to try to use the free one, then one day I did the math, charging from 40% to full saves me less than a dollar at home.
I just charge up at home rather than deal with those EV morons.