Of course it's morally incorrect to do everything that you mentioned above. However, it is equally incorrect to sentence a man to death for said crimes. Two wrongs don't make a right
The point wasn't that "two wrongs make a right" at all. The point was that what is "moral" has no basis in concrete or measurable reality, so it shouldn't reserve a place in the lawmaking process.
The entire concept of human incarceration is to remove members we deem unfit for our society, from society. It has nothing to do with what's moral, it's purely about what benefits the people on the other side of the gate, that's how it's always been. By nature, this concept includes capital punishment.