Nale committed premeditated murder.

Certainly there was no law broken, but the fact remains that from any pov Nale plotted to take a sentient life without just cause. He could not claim self defense, protection of innocents, or even action for the public good. In fact, he was himself as much a danger to the public as Malack, and he was not deputized to dispense justice.

There is no heroic way to commit murder. It is always an act of Evil.