I think that Sam should side with his father but I would understand if he sided with Stick, he has watched his father protesting all his life and at the very beginning of the book, (pg. 4) Sam says, "Father would say, you get enough people to lean, and the wall will move. I used to believe it but I just wasn't sure anymore."  He is basically saying he used to think that his father's non violent ways were able to get through to people but that as times and as the people as a whole have changed and as Sam has grown older and smarter he just doesn't think non violence at all times will get through to people anymore.  I think he should definetly side with his father but i would understand his reasoning, even if i don't agree, if he doesn't.