Sure - since they are not brainwashed, any more than you or I, Joey. They're adults, they volunteered. What really kills you guys (no pun intended!) is that there exists another point of view on the war, a valid one, one which since you cannot agree with you seem sometimes to flounder around looking for reasons why, as here.
And even when they tell you to your face that they support this action and why, people will still dismiss them. That's too bad.
250,000 protestors in NYC? There's a hell of a lot more of us in the US who don't demonstrate in support of the war but nonetheless do support it in ways that make the troops aware of it - letters, emails, packages, etc.