I think you are grossly underplaying the consequences of that plea deal. Six months (or less) in federal prison would still have him labeled as a "convict" and he would have lost numerous civil rights (voting being one) as a result. Needless to say, he would have to carry that label for the rest of his days as a US citizen. From what I understand, Aaron did not want to carry that cross, more so since he considered himself innocent. Hence, in protest, he took his own life. I am neither condoning nor criticizing his action and his final decision, as I am in no position to do that. However, I strongly doubt it was as simple or straightforward as you'd like it to appear. If you are a friend of Aaron's and you have come out publicly (on HN) as one, perhaps you could explain the reasoning and motivations better than most of us. Why not do that, instead of oversimplifying the whole situation?
Soldiers go to war knowing they can be killed. That doesn't mean when the enemy kills US soldiers, we should just shrug and say "well, they knew the risks, who cares?", does it?