They had three sons (Simione Ramacake, Ropate Rakula, and Atunaisa Taleasiga), and one daughter (Asenaca Tania Tuivanuavou).
After working as a meteorologist in Nadi, Siwatibau was posted to the Meteorology Office in Wellington, New Zealand, where he decided to study economics at Victoria University.
When Fiji gained its independence from the United Kingdom in 1970, Siwatibau was appointed the first native-born Director of Economic Planning.
In 1988, he left Fiji for six months to pursue a fellowship at the Australian National University, and on his return, he was appointed Head of EPOC (the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) Pacific Operations Centre in Vanuatu), a position he held until 2000.
Siwatibau was not a party to the plot and had no apparent sympathy with it, but Speight may have wanted a respected name to lend legitimacy to his rebel government.