The question in both the Carson and Huffington Post cases is framed in such a way that it becomes less about the utilitarian principles it's clearly trying to tap into and more about the logistics of time-travel, which I agree is utterly beside the point.
A more relevant and more direct question would be: Is it morally right to kill an infant to save 6~ million innocent lives? And if so, would you do it?
I still think taking the trolley problem to such extreme lengths is banal and facetious, but it is somewhat relevant to the role of POTUS. Since drones have and do kill children it's a question that deserves humouring (though the baby Hitler case is wildly anomalous due to the fact that in real life we have nowhere near the level of certainty that killing one child would save so many people as we do in that case).
But did you bother to watch?