Actually, I'd like to think this was heat of the moment. Cause as everything was going to s**t, he had no hesitation when it came to killing both of the scavengers. (I'm in the firm belief that's what they were) And once everything settled down, he began to realize how far he went. Cause he attacked one to "protect" Nova, but then executed another who was begging for their life. People can become something scary when they are pushed. But when the "combat high" ends, they go back to being their normal selves and begin to register what they just did.



That's my way of seeing this.