For Randy, performing his morning ritual of shaving and showering—both of them "painful luxuries"—makes him feel connected to the world before The Day (8.1)
There's just one problem: "his razor [is] a six-inch hunting knife" (8.2). Sheesh. A knick with that'd knock off your nose. As painful as that sounds, Randy's plus-sized razor provides an extra layer of symbolic goodness for us to enjoy.
Even though he's doing something he used to do, he's doing it in a different—and far more barbaric—way. It can't be the same as it was before; he's living in a different world.
Eventually, Peyton discovers some secret shaving supplies stuffed in the attic, which makes Randy's morning ritual a bit more efficient—and a lot less painful. Even without this sudden technological upgrade, however, Randy would've kept shaving 'til kingdom come. In a world gone insane, you've got to grab hold of whatever piece of sanity you can.