Good question.
Another article has more detail. Looks like Dubai was an interim port, but the parts were originally from Germany, they just figured it would be too conspicuous to go straight to Libya.
"Officials said the interception of the cargo, worth tens of millions of dollars, was a factor in squeezing Libya to give up its deadliest weapons programs.
The shipment was headed from Dubai in the United Arab Emirates -- an interim transshipment point -- aboard a German ship, the officials said. With help from the German government and the German shipping company, the United States was able to get the freighter, BBC China, diverted to a southern Italian port shortly after it passed through the Suez Canal.
Officials boarded the ship in Italy in early October and seized the cargo, which was not listed on the ship's manifest, U.S. officials said. The craft was less than two days from docking in Libya."
http://www.dfw.com/mld/dfw/news/nation/7612880.htm