I consider it likely to be beyond the point of no return if 1) it is a cockerel, a cockerel should be least likely to attack you because its still a teenager and cockerels are naturally submissive in the chicken pecking order to a mature cock. and 2) the aggression takes the form of constant flogging as if he’s trying to spur you. A rooster should never, ever, under any circumstance, attempt to flog or spur his owner. Any consistent spurring or flogging behavior is sign of the defect and either has to be accepted or culled. It can never be trained away because you can never train a rooster to not attack a rival. The defect is not the aggression the defect is in aiming the aggression at a human as opposed to a rival rooster. Attempts to assert dominance over said rooster are only temporary just as that rooster’s submission to a rival rooster is only temporary.At what point do you consider this Aggression to the point of being “persistent and severe”? — While he still a Cockerel, and before he has a chance to become a mature Roo? If so, then IMO it’s too early. I think what myself and @Tonyroo is saying is that you gotta let a cockerel be a cockerel, try to understand them, and give them a chance if you can as you may be cheating yourself of a really good Rooster that will one day save you Layer hens from danger and lay down his life for them. I mean, what better protection for you Flock can you ask for? To me, it’s definitely worth it! Roos get a bad rap, that’s for sure
I am also convinced that in addition to having a defect where human and rival rooster is not distinguished, some roosters attack out of enjoyment. My great, great, aunt had a Rhode Island red that would plan his attacks and pretend that he wasn’t going to attack. He’d fake out like he was pecking then he’d attack when the person turned their backs. He would never attack when being stared at. My great great uncle would knock him unconscious with a cane but that only taught him to be sneaky. That rooster terrorized the farm for a decade until he was culled unknowing to my aunt. I am convinced that rooster enjoyed attacking and could be considered a sociopath to the extent that any bird could be.
A rooster that may gently peck its owner out of frustration or begging for food can be corrected. That’s a different kind of aggression. One of my game roosters will gently peck me when I’m doing something he doesn’t like and I can verbally correct him and he won’t peck again in that context. He also liked to pull my boxers down from the rear when he was a very young cockerel if I went outside in them. He never makes any attempt to flog me. None of my living game brood cocks have ever tried to flog me at any times in their lives.