This conduct is worthy of man; for what advantage does he gain by vengeance?
The two actions are equivalent; if one action is reprehensible, both are reprehensible.

The only difference is that one was committed first, the other later.
But the community has the right of defense and of self-protection; moreover, the community has no hatred nor animosity for the murderer: it imprisons or punishes him merely for the protection and security of others.

...
Thus when Christ said: "Whosoever shall smite thee on the right cheek, turn to him the left one also," it was for the purpose of teaching men not to take personal revenge.

He did not mean that if a wolf should fall upon a flock of sheep and wish to destroy it, that the wolf should be encouraged to do so.

No, if Christ had known that a wolf had entered the fold and was about to destroy the sheep, most certainly he would have prevented it.