I can't even believe I have to say this, but NO, Superman would not be okay with the government asking him to become an executioner...
And how would he kill them exactly?
Beat their skulls in with his fists? Choke the life out of them with his bare hands? Burn their flesh with his heat vision?
Why are we even talking about this!
Superman: Don't be afraid.
Lois: I'm not. Helicopters, danger, go, go, go! Then we'll talk.