I'm stretching a bit on this one, but I don't think we're even 100% sure that knocking Max out automatically negates his control of Superman. He was already controlling him with subliminal codewords and across vast distances. In retrospect I'm kind of surprised that killing him wouldn't somehow trigger an even worse response in Superman, though I suppose the point was that he didn't ever expect anyone, least of all Wonder Woman, to actually go through and kill him.
(Although his death did actually trigger Brother Eye into going into a doomsday endgame scenario)
You know, you can take of this and apply it to just about any hero and villain. That's how loopy and slippy the logic gets.
Yeah, but that goes towards almost every powered Super Villain nowadays. Why not just kill them all with this logic?
You can't apply it to just about any hero or villain. The equivalent situation would be the equivalent situation: "An irredeemable villain gives a hero no choice but to kill them, either by mind-controlling Superman into putting lives at risk, or by any other means." And not just the situation, either; we're talking about all sorts of different heroes and villains with all sorts of different temperaments, power sets, and options at their disposal. Superman himself probably would have reacted differently than Wonder Woman did if their positions were reversed, but they weren't. We got the situation that we got. These stories would be pointless to read, after all, if every single confrontation between heroes and villains could be boiled down to an easily-predictable template every single time. What if Batman was in Wonder Woman's shoes at that point in time? What would he have done? Green Lantern? Aquaman? Zatanna? What if the villain in question was Despero or Grodd instead of Max? The options and circumstances change for all of these, and the logic that I applied to Max wouldn't apply to all of them.
Circe, for instance. She's got godlike magical abilities, controls minds, turns people into animals, is all-around an incredibly dangerous foe...but she instantly loses her powers and becomes a normal woman when you surround her with moly. That makes
incarcerating her a very workable option, without having to resort to mind-tampering. Also, she's been shown to be open to reform in the past; there was a time where she was even Diana's ally. Finally, the existence of her daughter Lyta gives her something to reform for. Immediately we see how different she is from Max and how the same logic wouldn't apply to the two of them at all.
And again, Wonder Woman has never subscribed to the no-kill rule. Yes, she has displayed mercy and redeemed quite a number of foes...
and she has also killed her enemies when the situation called for it. If you place her in a situation
exactly equivalent to the Max Lord scenario then, yeah, I would
totally expect her to do the exact same thing. The times where she killed Deimos and Medousa, for instance, are very comparable: lives were at risk and she definitively ended the threat. No one seems to want to concede this point, but the only difference between them and Max Lord was that he didn't have snakes for hair.
And none of this is even touching on the fact that the JLA itself
has come across situations where it apparently decided that it was okay to kill its enemies. The JLA killed Gamemnae in the Obsidian Age. They killed Z in New Maps of Hell. They killed Imperiex by tossing him at the Big Bang. They were fully prepared to kill Fernus, despite the fact that he was once the Martian Manhunter. (Superman's exact words: "Finish this. Whatever it takes.") (Hell, arguably they
did end up killing Fernus if you take the position that he was a wholly separate lifeform from J'onn, at the end) There's probably a ton more instances that I can't think of off the top of my head. There is such a thing as always trying to find a better way, but the fact is that we've all seen many instances where superheroes were forced to go with options other than incarceration or redemption. Sometimes it has to do with the species of the foe in question. Other times it has to do with their threat level (Gamemnae was human). And we probably didn't even bat an eye when we read them.
And this, too, I think is a problem. They aren't cops, they're superheroes, and it's not the same. I don't remember the issue, but there's an old Legion issue where Superman defends a non-powered person for killing, but still condemns superheroes for killing, because they have powers and ways to prevent that from happening. Not sure on the writer or if he meant this with the story, but it serves very interesting as a commentary between the real world and the superhero comic world, and how they do not connect logically.
I do think that this is the most defensible argument in favor of superheroes not killing; they're not cops, they are not licensed by the authorities for lethal force, their one and only job is to subdue criminals for due process. If the law decides not to pursue capital punishment, well, that's up to the law to decide, not for superheroes.
But that's a
legal issue; it has no
ethical foundation. Ethically, there is no difference between a cop or a superhero killing to save lives when there is no other option available to them.