CA wouldn’t allow protesters in war time. When the left gets mean they mow down all opposition. Think of red Russia in 1917.
I get the concept, i'm just not sure it would work the same in California of 2017. These young people are not used to hardship and adversity. They will balk at doing anything hard and "not fun", like fighting people with guns.
Will there be enough murderous "officers" to scare the bejeebus out of them and make them fight? Who's to say they won't run away at first chance? Or turn their weapons on their leadership at first chance?
I see discipline as being horrible, especially if they have officers murdering people to keep them in line. This might work better on people accustomed to suffering, but a lot of the pampered snowflakes would do everything they could to get away from it.
There are a lot of things which would have to work out right for the communists to get this thing to work.
You also haven't addressed the problem of keeping the food, water and electricity flowing into the cities if people outside the cities decide to cut it off. Just a taste of Stalingrad would probably have them surrendering.
I don't know, I can see it going several different ways, one of which is the way you have suggested.