Obiviously he was not required to recite this:
"I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state or sovereignty, of whom or which I have heretofore been a subject or citizen..."
(Shrugs) Take it up with the INS; it can't be taken away from him now.
"...a 5-4 decision by the U.S. Supreme Court in 1967 made it all but impossible for someone to lose U.S. citizenship unless he or she wants to give it up.
"The case involved a naturalized American citizen originally from Poland, who moved to Israel in 1950. Beys Afroyim tried to get his U.S. passport renewed in 1960, but the State Department turned him down. Afroyim had voted in Israeli elections, which meant he had automatically lost his U.S. citizenship, the department said.
"The Supreme Court said the 14th Amendment effectively elevated citizenship to a constitutional right and ruled that it can be lost only if renounced."
http://www.post-gazette.com/nation/20020515dual0515p4.asp