Conversation so far:
what did Leonard Bernstein have to do with social activism?
Bernstein would go on to fight for everything from the influences of "American Music" to the disarming of western nuclear weapons.
Are there any other interesting aspects about this article?
He was blacklisted by the US State Department and CBS in the early 1950s.

Question: what was he blacklisted for?
Self-contained rewrite: what was Leonard Bernstein blacklisted by the US State Department and CBS for?