I think that's a bit of a puzzling statement with regards reflected light. It almost implies that previously they thought it wasn't reflected?!
What we do have to consider in all of the photos is that the bright spots are massively over exposed and as such, their apparent brightness won't be altering across the sequence of images as it probably is doing in reality.
Absolutely fascinating though! I hope it doesn't turn out to be a chunk of ice. Would love to see a spectrographic interpretation though.