The article seems to be making a lot of assumptions. For example another explanation could be that crime is just seasonal.
People who are less well off would probably be able to survive on less during summer when they don't have heating costs. Or maybe they're just in a better mood.
"[The increase of the period of daylight saving time by four weeks] produced a useful natural experiment for our paper," authors Jennifer Doleac and Nicholas Sanders write at Brookings, "which helped us isolate the effect of daylight from other seasonal factors that might affect crime."
People who are less well off would probably be able to survive on less during summer when they don't have heating costs. Or maybe they're just in a better mood.