I like the alternate dialogue for Johnny Quick, though - it’s always nice to see a villian redeem himself.

…this one has one of the more badass Batman moments I can recall. He actually knowingly kills two of the bad guys. That’s the kind of Batman I want to see.

And with all due respect, I feel like you’re kind of grasping at straws to explain away Batman’s killing of Johnny Quick. One could very easily accomplish the same thing, stay true to the characters and introduce no ethical dilemma. Off the top of my head:

BATMAN: The only way we can follow Owlman is if we can find a way to create vibrations at 80 zillion jiggywobbles –
FLASH: I can vibrate at 80 zillion jiggywobbles!
BATMAN: No, I can’t let you do that. Moving that fast — even for just a few minutes — could kill you, Flash.
FLASH: But Batman, I –
BATMAN: We’ll find another way.
JOHNNY QUICK: I’ll do it.
FLASH: But you heard Batman — it’ll kill you!
JOHNNY QUICK: No — it *could* kill me.

And then Johnny Quick could give a little speech about finally doing something to help someone, blah blah. He could even throw in a cocky (but knowing) dig at the Flash about doing a better job too. Look at that — no ethical problems, kept Batman as the somewhat patronizing know-it-all, kept Flash earnest and compassionate, and redeemed Johnny Quick. It’s a completely uncomplicated scenario that took me all of five seconds of thinking.

This is kind of a technicality, but Johnny Quick didn’t actually die, he just sort of closed his eyes. It’s implied, yes, but not stated. I also think it’s worth pointing out that while Batman knew a speedster would “burn himself out” keeping a portal open to the multiverse, that’s not the same thing as knowing it would kill him.

As for Owlman, he was just stuck in a situation of his own making (actually, with a bomb of his own making). Batman didn’t kill him, he just sent him somewhere where he couldn’t destroy all of reality. Again - implied/likely death is not the same thing as killing someone.

Also, I think Owlman’s motives were perfectly clear - he’s a nihlist. The only difference between him and Darkseid or Thanos is his mortality, otherwise he’s pretty much working from the same motivation and towards the same goal - annihilation.

Now I’m not saying goons like The Ventriloquist and Mandrill deserve to be executed instead of being sent to maximum security, but it makes sense for the more dangerous guys like the Joker, Deathstroke, Carnage, Bullseye, and yes, Prometheus. These men kill for fun, and as soon as they get out of prison, they’re going to do it again. It’s not a matter of if, it’s a matter of when.

Take, for example, when Wonder Woman killed Maxwell Lord. With a brainwashed Superman under his control, Lord was the most dangerous man on Earth. If Wonder Woman hadn’t killed Lord, Superman would have killed her, and then he would have moved onto the rest of the superhero population. Locking Lord up in prison wasn’t going to do it. Sometimes murder is justified in the comic book world, it’s as simple as that.