The cable does get pulled out from the liner but not all the way. When you use a solid core cable its easy to feed it back in the outer. The cable on the shutoff is usually mounted to a release lever, which in turn is attached to the release pin. when it is tripped from the bumper, it releases the shut-off and then continues to get pulled out of the outer cable until your truck stops. OBVIOUSLY THIS IS ONLY IN A BREAKAWAY/HITCH FAILURE SITUATION.
-Tom