Quote: No. Dogs are NOT 100% a product of their owners. That is denying the reality of the fact that we successfully breed traits in and out of them, including aggression. That is also denying the reality of the fact that dogs are able to make their own decisions. Otherwise, you are claiming they are programmable robots that cannot be bred to be better or worse at any behaviour. If that's you claim, you would need to brush up on the history of the dog.
Some dogs that have gone on to be maulers are products of the best owners --- and the worst ancestors. Some of the best dogs are products of the worst owners, conversely, and this is not uncommon either. These are actually well documented facts. Some of the best and smartest owners/trainers have had to have dogs put down or caged like wild beasts. They can have great success but dogs have their own minds. At the end of the day, MOST dogs are products of their owners, but some will always turn. Some dogs, due to our bad breeding, don't see how mauling is not acceptable, like some pit bulls wagging their tails as they maul multiple people one after the other after the other. If you do even a little research into breeding traits into working animals, you will see that the human has great influence, but not total influence.
If you keep and breed an animal which harms humans, you are to blame for the next generations of dangerous creatures it produces, and the human injuries and loss of life that eventuate. It's a terrible shame that great roosters are dying for want of a home and people are keeping and breeding killers and maimers. Sometime in future the rooster you spared, or his descendants, will kill a human child. It's not uncommon at all. Anyone who spares a violent rooster should be aware of the eventual result and sooner or later that will be the death of a toddler or small child. An animal showing potential for aggression may be able to be reformed. Once it has committed to aggression, that's the end of it, unless you believe that animal is worth more than a human. Which some people do believe.