You think the kids can unlock the charge port but they have no ability to plug in?That doesn't really make sense.
First off, it's not dangerous... EV charge ports aren't energized until a plug is connected. It's safe to stick fingers, paperclips, dirt, whatever in it (safe for the human at least, they could damage the port).
If it were dangerous, we should be much more worried about all the Teslas sitting unlocked in garages (walk away lock is often turned off at home). Much more opportunity there for kids to interact unsupervised with an unlocked Tesla in their own home.