A takedown is possible but strange, he gets pulled out of the top of the cage. The Golden Path guy guarding him started shooting at me when I did though, so I had to kill him too. I then tossed De Pleur off the cliff and threw a Molotov at his corpse to give him a proper Kyrati cremation.
I can't feel sorry for this psycho slime bag as some have mentioned. Anyone whom can rob jewelry for his daughter off the corpses of innocent, tortured civilians needs to be put out of his misery.
It's one of the senseless parts of the story regarding Noore and Golden Path dialog though. Noore wants you to kill him, Sabal even says I wouldn't blame you if you'd killed him once you deliver him, despite first saying he wants him for questioning. And there is no option to kill him once captured, yet you can shoot him in the head as he's lying there with no effect save for blood spattering.
I would have liked an option to assassinate De Pleur at City of Pain, and in turn that could save Noore from committing suicide, because he'd never had even known about Min killing her family if Ajay hadn't been told by De Pleur then telling her himself when he confronted her. If after ALL that Ubi still wanted Noore dead, they could have given her an honorable death by having her lead a raid on another location only she knows about, to try and gain Sabal and Amita's trust. Maybe a small heli base or something, where just as you think the entire base is captured, she gets shot by a hiding sniper.