Graceful Restart is not designed to maintain forwarding in the event that a router is intentionally shut down; it is only to keep forwarding working long enough to perform a soft reboot on one controller at a time (of two or more controllers), i.e. to let firmware updates take effect. In effect, the functionality puts a "pause" on routing protocols so that surrounding routers don't panic when a peer isn't responding to BGP/LDP/etc. Then, when the reboot is complete, the peer routers can rebuild just their relationship to get back in sync, instead of reconverging the entire path.