I get you, but rhetorical power is just another form of power. Carter maximizes the power of his truths by eschewing wealth and direct organizational power.
It's true (pretty much by definition) that rhetorical power is a form of power. But it's a further, cynical step to conclude that if someone acts in a way that confers rhetorical authority, they must be doing so just for the sake of that authority. You're assuming away the possibility that someone might be genuinely acting, at least in part, from principle.
I disagree that it's cynical. I think maximizing the power of your ideas and principles is laudable, and can have great returns. Tying ethics to tangible reality increases the value and urgency of ethical behavior.