The easy and most effective fix is to remove the external USB port and put an internal one under a locked door with a killswitch and no space to close the door with anything plugged in. If the door's open it physically cuts power to the motors.
I do like that solution. The problem is than a ton of casinos have it. So the actual fix is more of a retrofit than a redesign to change where the USB is, which would require a recall.
That's a bit unfortunate. The problem with trying to fix this in software is that it's only a matter of time until someone manages to get around the fix. And any hardware fix would require a redesign anyway unless it's an add-on module, but that could be unplugged.