Probably the researchers are thinking about morality rather than risk because risk is very logical, and our brains are REAL dumb. We’re terrible at calculating risk automatically (or calculating anything automatically, really). Our brains don’t do anything like the math you just did. The morality lens is much more in line with what our brains are wont to do (empathize with anything that has a face, identify strongly with people and things even loosely associated with “good,” take as many shortcuts as humanly possible, etc).