Chickens are actualy as intelligent as dogs. And you can train them. I know cause I have. Watch the Bock and Roll band audition for America's Got Talent, soooooo good!I agree no one should ever hit or strike a rooster. IMO it is more humane to euthanize a man-fighter.
I don't really agree with your linked article about rooster socialization. Chickens don't have big brains and 99% of their behavior is from genetics or imprinting. I have not heard of anyone successfully training a mean rooster to be nice.