The nuetral safety switch is located under the shifter and only keeps you from taking your car out of park unless the key is in the on position and your foot is on the brake. It has nothing to do with not being able to remove the key from the ignition. The problem is the Park Lock Solenoid behind the ignition.
And GrandPrixlbc, if you're genuinely concerned about your passenger reaching over and removing the keys while you're driving.... then you should seriously reconsider who you let in your car in the first place.