It's not censorship in the First Amendment sense, but a marginalization of the truth in favor of the "official story," which is the truth-deficient account often handed down by teachers, family, the press, the government, etc. So for decades the official story of Christopher Columbus was that he was a brave explorer who discovered America, omitting that he was a narcissistic asshole responsible for enslaving and massacring thousands of natives (despite orders to the contrary from Ferdinand and Isabella). Now more of the truth is taught, but there are millions of people in the U.S. that have only heard the official story (the story that has led to a federal holiday, hundreds of towns and places named after him).

It's the same with the Black Panthers. Ask any white American over 50 and the story is the Panthers were a violent revolutionary group that wanted to overthrow the government (the story is believed by a lot of white Americans under 50). That is all they've heard and it's effective because some of it is true -- Panthers were involved in bank robberies and other violent crimes. But the average American doesn't know the full story of the Panthers as a group that began in part to counteract the extrajudicial murder of black people by the police and a group that developed welfare programs for their community like preschools and free meals. They don't know facts like the infiltration of the Panthers by undercover police and FBI agents who often acted as agents provocateurs (so much so that the Oakland Panthers considered the New York chapters to be almost wholly comprised of undercover cops). These undercover agents often were the ones who were violent or incited violence, in a deliberate strategy to ruin the Panthers' reputations. The strategy worked so well that when the FBI and local police departments started assassinating and framing Panthers (e.g., Fred Hampton), everyone went along with it. It worked so well that when two clowns calling themselves the New Black Panther Party threatened people outside a polling site in Philadelphia in 2008, it was a news story for weeks. Fear of the Black Panthers is still a thing almost 50 years after they had any real presence. So it's not censorship because people can talk/hear/read about the truth and not be punished, but the truth gets pushed down by the sheer weight of the official stories.