I've got 40 rejected pictures from the same batch , shot with a Nikon D7100 in the same day , with : '' Excessive artifacts/noise can be caused by low light, bad camera settings, strong compression or excessive post-production. ''
Your second has been indeed over sharpened and exposes therefore artefacts. I haven't checked the picture in Photoshop, but I think that there are also exposure issues because of the image complexity. The people may require model releases (different refusal reason), even that they are very small.
ABAMBO | Hard- and Software Engineer | Photographer