There is no local indication that this discovery is related to wreck of the "Norwich City."
Link
Now what stikes me is that Gallagher is there on the ground post Norwich City but pre main settelment, LORAN station and other visitors. Quite clearly he states that there is no evidence of a camp or other use by the Norwich City Survivors.
Well, he doesn't show his work.
I don't think we can absolutely exclude a visit by sailors from the wreck some time between Saturday and Tuesday. People did explore the island to some extent, looking for food and water.
It's not clear what Gallagher would have taken as evidence that NC survivors had been there.
It's a comforting thought and observation, but I wouldn't classify it as definitive.