You can get a lot of people to agree that torturing suspected terrorists is justifiable so long as it gets you actionable information. That doesn't make torture okay. You can get a lot of people to agree that murder is justifiable in the case where the person killed someone you care about. That doesn't make vigilante justice okay. The entire existence of the field of ethics is predicated on the idea that morals are not intuitive, that we need to look closer and think harder, and that we can't just go with our gut. More generally, philosophy assumes that "common sense" is a contradiction because if all reasonable people agreed on everything, we wouldn't have anything at all to discuss.
It might be a little mean to poke fun here, but when a Harvard professor has based his entire career on the trolley problem, and he hasn't understood the trolley problem making fun seems nicer than the alternative.