I thought it was BS too. But even with BS there can be elements of truth. It can be easily verified on the WT CD-ROM that Gilead School graduation is around Sept. 11, and for 2001 there is an account of what the graduates were doing:
yb03 p. 8 Highlights of the Past Year
The World Trade Center Disaster: The graduation of the 111th class of the Watchtower Bible School of Gilead was held on Saturday, September 8, 2001. Three days later, on September 11, graduates and their families were touring New York City, in the United States. That day began warm and beautiful with clear, blue skies. Then, at 8:46 a.m., a commercial jet crashed into the World Trade Center north tower in lower Manhattan. Minutes later another commercial jet slammed into the south tower.
Whether the entire GB were there touring and had a lucky miraculous escape ... I think that story would have already been milked for all it was worth by now if it was true. It's the first I've heard of it.