Those killings I personally have no problem with. Killings where somebody will be murdered unless the murderer is immeadatly killed are fine. It's just that some people seem to want 'brutally kill criminals, even if they can easily be taken alive with no threat to others' style of superheroes. Superheroes serve as cops for threats that normal police can't handle, and while police can take out people that pose an immeadiate threat they cannot shoot captured or unarmed criminals just because of what they did.