Haven't read the thread, but based on the title, "Just kill 'em" wins, obviously.
It's not my job to dumb down villains or, really, "balance" the PC's survival in any way. Ensuring the PC's survival is what the players are for!
Keep your character alive, succeed at the challenges that arise (which your own actions -or inactions- may bring about), hopefully become rich and famous in the process of repeatedly saving ever-growing sections of the world...and possibly, eventually, ever-growing sections of the cosmos. That's the game I play.
Monsters that would normally be out to kill you (for whatever reason)...will kill you given the opportunity. Creatures that are looking to capture you (for whatever reason), will capture you given the opportunity. Give 'em too much trouble, they're likely to kill you instead (unless some extraneous detail prohibits them, like fear/respect of a commander's orders, an attractive enough bounty/pay out, etc...).
The villainous monologue is fun and dramatic, and of course building drama and tension is essential to a successful game and story, but...I can't think of a single time I ever pulled a James Bond-esque "left to die/slow death trap." Thrown in chains/the dungeon and left to rot? Sure.
If it is in the interests of the NPC for the PCs to die/be dead, and their alignment isn't going to prohibit them, then that's what they're going to try to do. If the PC's don't survive?...Start rollin' those d6s.