Despite his fondness for atrocities, Kurtz has a code he lives by, and the thing he seems to hate most is dishonesty. In Apocalypse Now, he thinks the generals who are supposed to be commanding him are hypocrites, since they claim that he's being unlawfully brutal while he's only doing what they want him to do: win the war.
In Kurtz's eyes, brutality is the truth—it's the only way out of the conflict. It drives him nuts (literally) that the same army that sends young men to kill won't let them paint obscenities on their airplanes because it's immoral. In his eyes, he's just being authentic and honest about what he's doing. The real deception is that the war's being fought for some noble cause.
Questions About Lies and Deceit
Why does Kurtz think his commanding officers are liars?
What kind of deceit does Willard object to?
When Willard first meets Kurtz, he's pretty honest with him about why he's there. Why do you think he didn't try to hide his mission?
Chew on This
Kurtz's brutality is just a form of honesty. His superior officers burn people to death with napalm, but they claim that what Kurtz is doing is wrong. They can't handle the truth about their own actions, so they need to turn Kurtz into a scapegoat.
Kurtz's pretense of his clear-eyed ideals is just as deceptive as his superiors'; he's just hooked on power.