I honestly don't know how that defense will work. I'm generally pro-law enforcement, but I couldn't buy a self-defense argument here, or defense of others. There was just no reasonable threat.
I’m generally pro-LE too, but I agree—self-defense sounds like nonsense to me. Defense of others? Who? The partner who would have gotten his head blown off if he’d made a sudden move? “Reckless disregard for human life” sounds more like it.
And they’d been called out, on the possibility that a woman was being attacked. So, if an agitated woman in night clothes rushes up to their car, he shoots her?