I seen this scenario the other day in the TV series The Good Place (Series 2). I can't remember which episode.

I personally feel that the question itself is a red herring as there is not enough information to work with. What it does mean is that humans should not play God as God has more information to work with when it comes to making a decision.

God would know what was the most important for humanity, a machine or human could never reach that type of intelligence.

The one person, may in the future, become a world leader and bring peace all over the world hence killing him/her may be the difference to the existence of humankind. (We will never know what the butterfly effect would be.)

However, if there was a choice to be made, the person, or people/group/organisation, that caused the question in the first place is where the responsibility lies. The person on the train having to make the decision is innocent due to the limited choice of what they are given hence it does not really matter what their decision is.