His military service entitled him to American citizenship, which he adopted on 26 July 1946. He subsequently re-enlisted in the U.S. Army and was posted back to Japan, joining General MacArthur's headquarters in Tokyo. Gamboa applied to re-enter Australia in October 1948, hoping to return to his family after his discharge in August 1949. His preference was for permanent residence, but he also applied for a tourist visa as a back-up; he assumed that as a U.S. citizen he would not face the same difficulties as before. However, the Department of Immigration informed the Australian Mission in Tokyo that he would not be allowed to enter the country at all, as he was non-white and his case would be a precedent for other Asian war evacuees to remain in Australia. In early 1949, Gamboa encountered Australian Associated Press journalist Denis Warner while waiting in an army post office in Tokyo. Warner's article about the case sparked a media frenzy, with coverage in popular daily newspapers and weekly magazines overwhelmingly sympathetic to the Gamboas and hostile to the government. Lorenzo was quoted as asking "why did they let me marry an Australian girl if they wouldn't let me into the country to see her?". The media coverage of the Gamboa case and other similar cases made the government's immigration policy an issue in the lead-up to the 1949 federal election. Calwell defended his actions during a campaign rally at the Brunswick Town Hall in November 1949, stating "there is nothing wrong with the Labor Party's administration of the White Australia policy". He said "I am sure we don't want half-castes running over our country", and told the audience that "if we let in any U.S. citizen, we will have to admit U.S. Negroes [...] I don't think mothers and fathers would want to see that". He believed that allowing compassionate exceptions to the White Australia policy would lead to a slippery slope in which thousands of other non-white immigrants would be allowed entry. The same reasoning was behind the passage of the "War-time Refugees Removal Act 1949", which allowed the government to deport non-whites who had entered Australia as refugees during the war. The government was not only accused of cruelty towards the Gamboas, but also of endangering the White Australia policy through an overly heavy-handed approach that was likely to antagonise Asian countries. Opposition Leader Robert Menzies attacked the immigration department's "singularly unpleasant process of victimisation", but reaffirmed the basic principles of the White Australia policy.