Gleyzer was part of the left-wing faction of the Peronist political movement, and a staunch opponent of Argentina's last military dictatorship (1976-1983).
From the start of his career all of his films were focused on the fight against social injustice and for political revolution in Latin America's countries.
His last major film, Los traidores (The Traitors, 1973), presents a strong critique of the right-wing faction which prevailed in the Peronist political movement at the time and which also played a pivotal role in Juan Domingo Peron's third and last presidential term, in 1973.
The film depicts how several union leaders had secretly and slowly aligned themselves —many years before Perón's comeback and inauguration for his third presidency— with the economical establishment, the military and United States's interests with the only goal of maintaining their personal power and enrich themselves.
Brazilian cartoonist Carlos Latuff created a cartoon dedicated to Gleyzer and the violently "disappeared" people of Latin America.