It's not about him being the equal of anyone.
It's about whether Lex Luthor is the kind of person who throws good money after bad.
For whatever reasons, we decided that killing Whale was better than anything else we could have done (e.g. giving him an ultimatum to get out of town, bribing him to get out of town). We hired a pretty good assassin. She gave it a good shot. She failed. Whale is alerted, vengeful, and afraid. It turns out that Whale was able to exploit loopholes in our defenses and get information that could seriously hurt us. Now he's trying to barter that for his life.
Why do we want him dead badly enough to accept a major setback? Why did we want him dead that badly in the first place? I doubt many of us would have voted to assassinate Whale in the first place if we didn't expect to get away with it cleanly. Now we're almost sure not to be able to get away with it cleanly.
There are reasons for Luthor to change his mind about killing someone other than "this person is my equal." Luthor's presumed superiority does not necessarily have to express itself through killing everyone.
We... never really used Bito. Bito is still out there.
Also, Bane clearly has a very great level of pride, and a fixation on destroying Batman that would seem weird* if we weren't playing a character who's about to do
one of the things you proverbially do not do, and tug on Superman's cape.
We may be able to get him to do things for us as a mercenary, but there are going to be sharp limits.
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*(I'd have expected him to only develop such an obsession
after arriving in Gotham, or at least the United States)
A reasonable approach- though as we just saw, it's possible for Lady Vic, or any assassin, to simply
fail.
The queen? Run that by me again?
That exposes us to his men and gives him a plausible opportunity for revenge.
If we wanted to use him as a commando leader of a mercenary unit, it'd probably work, especially since his men are so well armed. The problem is simply that he's too proud to work for us- we'd have to do something like integrate his men into our PMC and put him in charge of that, I think.
Attempts to sway Jonah Hex to the Luthors' side would probably have been more an issue for Leland or Leonardo.
Yes, but other crimes like "spying on everyone with a cell phone" and "having nuclear missiles" are harder to explain.
Fact: Whale's existence as a loose end is in fact on some level a problem.
They may become a threat.
The catch is, Whale's existence is a
smaller problem than some other problems. Whale apparently put considerable time and effort into making sure he could create a situation where once he knew we were after him, he could make us regret it. And he succeeded.
So now Whale is a threat, but he's a threat that becomes
actuality, that causes us real harm, if we continue to attack him. He's poisoned meat; if we chow down, we make things worse. Killing him right away in a decapitation strike might have worked, but Whale had good enough bodyguards that our attempt to do that simply failed.