What you say is correct, but this is an article about Joan Baez, not the American left wing, and that article does not mention Joan Baez at all (unless I am mistaken). For this statement to be justified for including in this article, there should be some documentation that her disagreement with the American left wing is notable. Otherwise, this is simply original research [ http://en.wikipedia.org/wiki/Wikipedia:No_original_research ]: "Do not combine material from multiple sources to reach or imply a conclusion not explicitly stated by any of the sources."