The song about Rubén Jaramillo by Ochs is a simplification of a long story.
Read about his early work in Morelos here (with English translation):
Instituto Jaramillo
Jaramillo fought with Zapatistas in the 1910-1920 revolution, and later was active in promoting farmers' rights. He convinced President Lázaro Cárdenas to build a sugar-processing mill in Morelos in order to make sugar cultivation practical. The mill was opened in 1938.
In 1943 Jaramillo formed the Agrarian Labor Party in Morelos. In 1960, he encouraged a number of land seizures, which brought the wrath of large landowners. In 1962, the police kidnapped him and his wife and three children, and killed them.
Donald C. Hodges, 1995, "Mexican Anarchism after the Revolution," protrays Jaramillo as an anarchist, but this label is at odds with his history, that of a man who flirted with freemasonry and the Methodist Church, and had worked on nationalistic programs. There is an online review of this book, but I don't have the time to look for it now.
I have not found a corrido about Jaramillo, but I am sure they exist.

We don't get current news of Mexico often, but last week thousands of small farmers with their tractors came to Mexico City to protest against the importation of cheap corn and corn flour from the U. S. and Canada. Bush and the department of State, and the Agriculture Secretary, made Mexico agree to the imports.
The small farmer in Mexico has made great strides, but still has a ways to go to get security.