For a brief glimpse of Robeson... check out this article from David Horowitz.
There is an immediate reminder of these connections in the Paul Robeson centennial that progressives are observing this year. In a variety of cultural and political events on the 100th anniversary of his birth, the left is celebrating the life and achievement of one of its greatest modern heroes. Robeson, however, is a man who also betrayed his friend, Yiddish poet Itzhak Pfeffer, not to mention thousands of other Soviet Jews, who were under a death sentence imposed by Robeson's own hero, Josef Stalin.
In refusing to help them, despite Pfeffer's personal plea to him to do so, Robeson was acting under a code of silence that prevented Communists like him from "snitching" on the crimes their comrades committed. They justified their silence in the name of the progressive cause, allowing the murderers among them to destroy not only millions of innocent lives, but their socialist dream as well.
... "Snitching" is how the progressive mob regards the act of speaking truth to power, when the power is its own.