Would Grace have gone to ______, IF he DIDN'T have the beetles, and had to ______?

#Would Grace have gone to save Rocky, IF he DIDN'T have the beetles, and had to fly the entire Hail Mary back to earth to deliver the taumoeba?

Nearly everyone would go to save Rocky with the scenario presented in the book and film. However lets imagine an alternate scenario that's more morally interesting.

Imagine if the PHM mission was designed as a return mission from the beginning. So no beetles, and the whole ship had to go back to Earth to deliver the solution.

Now Grace has to choose between saving himself and Earth, or saving Rocky and Erid. Then what would he have done? What would you do?