They have two choices.....leave or die. The tide of history is flowing out and they will be either drug out to sea or be drowned where they stand.
Harrison's best response would have been to burn the farm and buildings, destroy all the equipment, and salt the earth. There's something to be said for the "Wyatt's Torch" approach. Unfortunately, he no longer has the resources to salt the ground, but he could probably catch a few of the looters in a fire.
I cannot understand for the life of me why anybody would stay in that hell hole. It doesn't matter what you have or don't have except for your life. Stupidity there must be contagious.