Re: If the author wanted a "killing is always wrong" shpiel, he picked the wrong villains.
I'll add my agreement; Joker and Zsasz have have claimed huge numbers of new victims as a result of the Bat-Clan's (and to be fair, everyone else's) refusal to do what is neccessary to stop them. Joker and Zsasz have a right to live, but so did the hundreds (or Joker's case, thousands to millions) of people they killed since the first time Batman caught them. Their right to one day possibly be redeemed does not justify allowing them to murder at will until they feel sorry for it. Even if they're insane and not culpable for their actions they have to be stopped.
Besides, even if the Bats can't cross the line and kill, there are plenty of other measures they could take that would end (or greatly diminish) the threat. They could always steal a page from DKR and leave Joker or Zsasz paralyzed from the neck down, which still leaves the alive while making it almost impossible for them to kill again (and certainly never on the same scale).