The joke is, it's not his name. It doesn't have to be Ziad Jarrah. Using "Ziad Jarrah" is more of a reference. If you want, you can have the reveal just before the last commercial break, then, over the closing credits, have a newscast mention how Dwight's body was dug out of the ground because people thought it was one of the 9/11 hijackers, but that's pushing the joke a little too far. Maybe have it say "The Office" instead, both as a prank and a metareference to the show's ending?