Although the vast area and long coastline are good news, managing such a large indigenous population is also a significant challenge for Spain.
It is certainly impossible to kill them all; attempting to slaughter all the indigenous people in this region would mean killing over ten million people.
Such a massacre would be too insane, and the public pressure it would create is something the Spanish Government could not bear. If they really did this, let alone the Spanish Government, even Carlo would earn a reputation as a tyrant.
At that point, the international influence, status, and reputation of both the Spanish Government and Carlo himself would be severely impacted.
Even if Europeans seem indifferent to African lives, news of Spain massacring millions of indigenous people would lead almost all Europeans to condemn the Spanish Government's cruelty.
