I agree, the study is kind of stupid and proves nothing. Lots of follow up studies would have to be done to prove anything. For example, would any change in diet disrupt the circadian clock? Would changing the diet in light, allowing for adaptation, and then if the mice were put in the dark would it be disrupted? Too many questions and too many assumptions are made on this one study.
Mice studies are actually very good btw, mice eat and live very similarily to humans, yet everything is amplified on a 30:1 basis, meaning you can see the long term effects something would have on people in 1/30 of the time.