Planetary protection is very important. But we're going to need a sensible approach and balance between the colonists needs of survival and our desire to know more about ancient life.
One of ideas I've heard floating around is that burials be banned to prevent contamination. Shaking Martian corpses to sterile powder.
But in the very, very unlikely scenario it's required, NASA shouldn't have the authority block it off from the colonists who are on the brink of dehydration and death.