Wow I just tested that and yes anyone pressing the button on the handle can interrupt the charging. That's not good. It will start again once you release, but at some public charging stations that could be a problem as they don't restart automatically.
If you have set the car for scheduled charging it will not restart to charge if the button is pressed in some situations. I really think Tesla should change that! Maybe there is some safety law that requires a method to stop charging even when a car is locked.