In the movie Predator, near the end, after they try to trap the Predator in that net, and it shoots its way out, a lot of them die. One guy is badly injured, so Arnold and that girl help him walk. When the woman tries to pick up a gun, Arnold tells her not to because the predator didn't kill her before because she was unarmed, then Arnold calls the Predator a "no sport". How is only fighting armed people being a poor sport? Did Arnold ad lib this and fail badly?
It means exactly the opposite of your take on it. I think Arnold said "No Sport" to indicate that if she was unarmed, she would be too easy to kill; not sporting. If she was armed by picking up the gun, the Predator would consider her to be true sport, in a fairer fight.
Here's a sound clip of a quote from Blade Runner that conveys the same message more clearly:
Roy Batty: "Not very sporting to fire on an unarmed opponent."