How about the fact that a young clever men with top salary, beautiful girlfriend and comfortable life in one of the (supposedly) most developed country in entire world couldn't stand his own government's abuse, and decided to break the silence, knowing (Bradley M?) that his life is over.
Is that good enough reason for you? How about this: he promoted the truth, because otherwise had he not done it, we could have ended in a North Korea type dictatorship.
Well, I think government abuses falls under the umbrella of things that aren't peace. Thus, action against government abuses would be implicitly promoting peace.