This is just a rehashing of the Trolley Problem, but instead of just numbers of people they are getting more specific about the types of people. For certian questions, like whether I would prefer to kill a doctor or homeless person, I chose the homeless person because there's a chance the doctor would be able to help save the lives of others at the scene. It was a utlitarian calculation and not out of hatred for people who are homeless... and by killing the fat people, they would be useful in cushioning the blow for the people in the car.