What I would like to point out is that all roosters are aggressive. So the question becomes are they aggressive to humans? As a one that has a backyard flock with multiple roosters, Tom turkeys, living in the same area, I can safely say that the pecking order is established by the caretaker of the flock. Well, at least the tone is a more accurate description. With that said, how does one curb an unwanted aggressive behavior in a rooster? My first thought is punt! Yes, when that rooster comes at you you draw your leg back and punt! Let that rooster fly. What I would like to remind all of you is that rooster has a coat of armor in the disguise of feathers. Punting will not hurt nor kill the rooster.
In my travels I had a few very aggressive roosters. Punting helped curb the behavior of attacking people. Stressing again, it will not hurt the bird! It will teach that critter that there is something else bigger and you a’int having none of it!
Here is another thing that I gleamed from the Backyard Chickens link. “In the rooster world, he who runs away, walks away, or hides is the loser, these are his acts of surrender. I want to warn you: Never introduce a second rooster to a flock that already has one. They will most always fight to the death or until you can intervene.”
Not sure what bred of roosters that the individual had? What I can tell you in my eight years of chickens is that I have never had that issue. That is with a mixed chicken flock with six roosters, five Tom turkeys, and a mixed group of chickens and turkeys. There were around 60 birds all together.