They would of died anyway
Something I just realized. Even if their life support system worked and they made it to mars and back they would of died on re-entry anyway because of the heat shield failure.
The faulty heat shield wasn't expected. They were getting ready to put the astronauts back in the capsule so they would arrive to a hero's welcome. When the ship exploded the NASA officials were caught off guard and had to figure out a backup.
They were probably keeping the astronauts alive in case something happened where they would HAVE to produce them.