I could be wrong, but I understood Clint's statement to mean the movie is not about winning or losing, but mostly about the interrupted lives of young people.
I understand how you could make this judgment. But here's the whole quote in context.
'I feel terrible for both sides in that war and in all wars. A lot of innocent people get sacrificed. It's not about winning or losing, but mostly about the interrupted lives of young people.
I read the antecedent of the "it" in "It's not about winning or losing" as being "all wars" -- not "this movie".
And every war is ALL about winning and losing.
For Clint's sake, I'd like to think I'm wrong, but I don't think I am.
By the same token, I have no difficulty admiring the bravery and courage of enemy soldiers. But I don't like being asked to ignore their cause...