Well, it is not γερομάχος, rather χερομάχος. Which does mean labourer, from χέρι and μάχομαι (in the sense of working), the one who toils with this hands, a manual worker. Cf. ξωμάχος (εξωμάχος), the one who toils in the open air. Χερομάχος, now rare, was not so exotic a word some decades ago.