Sorry, SDAI. That's just the flip side of the same coin.
Cindy Sheehan's poor parentage and political beliefs drove her son to the military.
Casey Sheehan, an adult, enlisted in the military, and then re-enlisted during wartime. While you can judge from this that he probably supported the mission in Iraq, saying he was "driven" into the military by his mother's beliefs is not much different than the "brainwashing" argument his mother makes.
I have seen no evidence, even circumstantial, that leads me to think his decision to enlist--twice--was motivated by rebellion against his mother, although she was violently opposed to it.
The man was an adult, who made his own decisions, based on his own beliefs. Projecting other people's agendas on him isn't right coming from either side.