Point taken on the military aspect, although most conflict over the last decade or so could be categorised as guerrilla warfare - so if you are not willing to engage, no matter how difficult, you leave yourself at a strategic disadvantage. But on the particular issue I'm addressing - I don't remember any anti-war protestors holding placards reading "stop the war because we don't like guerilla warfare" !
In fact if anything - from what I've seen a lot of the positions could be categorised as
1) War is bad, so stop it. ( True, but naive)
2) Stop the War - as if it was merely a War between the US and the North which the US should disengage from to stop. When in fact
it was a war between North and South with the US supporting the South.
Also there appears to be a complete silence on the struggling South Vietnamese from the anti-war demonstrators - almost as if they were unaware they were actually there. And a complete silence too on their fate after the war - refugees, sent to "re-education centres", and the suicides of many of their officers. No one amongst the anti-war protesters seemed to voice any concern over their fate before or after. They appear to have largely been forgotten, although I found a website in which many South Vietnamese expressed their gratitude to the US for trying to defend them.