Often is is politically motivated, they use it as a character assasination and a way to hate on the "evil right."... instead of being genuinely opposed to this kind of war.
Remember when Clinton's war was going on? I don't remember the same amount of anti-war protests from the left then. So, the writer does have a point that the movement from the left is not always sincere.
As Tonto said to the Lone Ranger when surrounded by thousands of blood thirsty braves, "What do you mean "we" white man?"
I'm always said that the anti-war groups are not anti-war. That they do support war by America's enemies against America. The war is just another opportunity to get their "hate on" against the USA.
It's as simple as going to a "peace march" and counting and noting all the OTHER grievences the participants have against this country and what other groups and countries their signs, banners and flags support.
And thank the media [snicker] for their great coverage of that so that the American public is so well informed and knows of it.