Demons: Demoniac Nature

Q. If the same "detachment" perspective on moral values can be used both by the demon Kamsa (in justifying his killing of the sons of Devaki) and a divine avatar, it is hard to accept that such an approach could represent a true basis for morality. Is detachment a way to by-pass dharma/karma for a demon?

Q. 1. I'm wondering how individual free will factors into the verses and purports describing the species of demoniac life. Specifically BG 16.19 - 20.

Srila Prabhupada's purport states:
"In this verse it is clearly indicated that the placing of a Particular individual soul in a particular body is the prerogative of the supreme will."

"As for the demoniac, it is clearly said here that they are perpetually put into the wombs of demons, and thus they continue to be envious, the lowest of mankind."