When the Slovak National Uprising broke out in August 1944, Steiner was with his family in a partisan-controlled area and was unable to return to Bratislava. He survived the war with his wife and son in hiding in the mountains. After the liberation of Slovakia in early 1945 by the Red Army, he resumed his architectural career and also ran a rehabilitation center for Jewish children with funds provided by the Joint Distribution Committee. Although he sympathized with Zionism, he chose to move to the United States after the Communist takeover of Czechoslovakia in 1948. After a brief stay in Cuba, he was offered a position as chief architect in an American studio and moved to Atlanta, Georgia in 1950. He taught urban design at what is now Georgia State University while working for the architectural firm Robert and Company Associates in the 1960s. He designed houses and the Ahavath Achim Synagogue. He was also vice president of the Urban Design Department of the American Institute of Planners. In 2009, he died in Atlanta and is buried at Oakland Cemetery; his wife and two sons predeceased him. He was the last surviving member of the Working Group.