Parents cannot renounce U.S. citizenship on behalf of their minor children. Before an oath of renunciation will be administered under Section 349(a)(5) of the INA, a person under the age of eighteen must convince a U.S. diplomatic or consular officer that he/she fully understands the nature and consequences of the oath of renunciation, is not subject to duress or undue influence, and is voluntarily seeking to renounce his/her U.S. citizenship.
This section of the law was not added until 1981. The law in effect when Barry would have been adopted in Indonesia did not prevent him from renouncing his U.S. citizenship ... providing he ever had it. There’s no legal proof that he did.