I'm not sure what this tells us about Nixons right to have Allende deposed though.
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.
Its also worth keeping in mind that moral decisions have been explored for quite some time, and the novelty here is mainly the mode with which the population is sampled.
I am no expert at history, however, during the 1930's Henry Ford did something similar to introduce the Flathead V8. Factories were closed, hundreds of thousands made unemployed, then, in secret, Ford worked on the V8 and the factory to make the new cars. When he was ready the gates opened and new hires were made.