According to Snopes.com, the Honor Guard at Arlington National Cemetery did indeed keep duty during Hurricane Isabelle:
http://www.snopes.com/military/isabel.htm
http://www.snopes.com/military/unknown.asp
Although there are a lot of limits to their services, they
are permitted to talk (somewhat) during their training. There was a marvelous program on the Honor Guard on either the History Channel or A&E, following a few men throughtout their service. Just prior to Memorial Day, they go to every grave in Arlington, place a flag, salute it for a designated amount of time, and then move to the next one.