shooting Communists was ALWAYS a just cause, by the way
Exactly. As others have pointed out here, it's only because it seems the bullets are flying their way, that the leftists are suddenly concerned with defense. In Vietnam, there was no threat to western leftists, so it was convenient and fun to say things like "take up arms on the side of the Vietcong" while all the time staying in their comfy homes, going to their cushy jobs and sharing cocktails in indignation with their like-minded friends.