I don't think this is about creating realistic scenarios, but about finding out what people take into consideration when making moral judgements. The experiment seems to be designed to gather as many such preferences as possible.

The hope must be that if people consistently prefer saving the life of young people in this made up scenario they will have similar preferences in a more realistic scenario. Of course weather such a generalization holds will have to be confirmed by further studies. But this seems like a good first step to explore moral decisions more.