You are correct that it was an analogy for the election, but the point the analogy is trying to illustrate is precisely that if you actually and for real were faced with this situation and decision (assuming you love your parents, if not please substitute for the 2 living beings you love the most), that you would reject the decision and take any number of alternative actions that are available to you before allowing a loved one to be killed. Hell, a bunch of people would fight to the death in a situation like this.

The previous realization would then illustrate the hypocrisy behind expecting people to behave in a strictly utilitarian sense when you yourself would not when it involves your loved ones.