A longer shot of the nest would have also helped, so I could see what shape it was. Gerygone is usually suspended from a vine or some such. The egg colour is good for Gerygone: "white, lustreless and moderately blotched with varying shades of reddish brown and reddish purple" in my nests and eggs book. Unfortunately he then goes on to say eggs of most Gerygone and Acanthiza (thornbill) species are indistinguishable. So not confirmable. Did the nest have that big hole in the side? Seems unusual. For gerygone it is supposed to have a downward sloping entrance tunnel on one side.