pwc101 - The script does attempt to restart servers, but in the event that servers still can't be restarted, then a reboot will commence.
BTW, I figured it out. My path was right, it was that it needed the right permissions. Doing this worked from cron job:
exec("sudo shutdown -r now");
Whenever you want to use system-type commands, even within the root cron job (ie. crontab -e), you have to specify 'sudo' for some odd reason.