His drawings were not originals then, only copies. He must have been doing them as a sort of retirement hobby, he was an incurable amateur and enthusiast; if he'd become hooked {on these rock paintings} he would have combed the area for them, collecting them with his camera, pestering experts by letter whenever he found one; an old man's delusion of usefulness.
The protagonist in Margaret Atwood's "Surfacing" reflects on a man whose drawings lack originality, suggesting they are mere copies of existing rock paintings. This man seems to engage in this activity more as a casual hobby, perhaps as a way to pass time in retirement rather than as a pursuit of serious artistic expression. His lack of professional ambition indicates a sense of comfort in amateurism.
Furthermore, the text implies that if he had been truly passionate about rock art, he would have dedicated himself to exploring and documenting these works more rigorously. Instead, he remains an enthusiast whose efforts are marked by a sense of nostalgic longing for relevance, capturing the notion of an "old man's delusion of usefulness" in his art endeavors.