My guess is that Ayers (or whichever of the authors decided to put that name in the dedication) blamed the US government for Bobby Kennedy's assassination. I'm guessing that the authors of the book believed that Kennedy was killed by the US government because of his stance in opposition to the Vietnam war, and because they thought he would try to end the war if he was elected president. So if they believed that, and if they (like a lot of other people) believed that Sirhan Sirhan was framed for killing Kennedy, or as some people believe, that he was hypnotized into doing it, then they would consider Sirhan to be a victim of the US government and its war machine, and that this is why they included him in the dedication of that book.

I think people will find that most organizations like the Weather Underground do believe that the US government is responsible for the deaths of JFK, MLK, Malcolm X, and Bobby Kennedy.