I've only had roosters that got aggressive when they were at that hormonal stage and they calm down afterwards. Right now one of my Jersey Giants has only attacked us twice in 7 months, the other one did it once and it was MY mistake no matter what anyone tries to say.Wow. Lots of good ideas there in your post if you do have the energy to put into an agressive bird. That's too much time and effort for me. I'd just eliminate the problem and move on with other options.
And another thing comes to mind, why would you want a human aggressive cock in your flock passing on his human aggressive genes to his offspring? That is a trait I would actively be trying to breed out of my flock.
I think too many people try to off a cockerel without ever giving it a chance and they are missing out on a lot of good roosters for the future. I would rather try everything I could possibly do than give up. I'm not the type that just gives up because it's the easier option. I'm the person that does every possible thing to ensure that I did everything before I raise the white flag.
Most Cockerels get aggressive when they're hormonal. If I killed every single cockerel that has walked on my property from being aggressive, I would have none. The cockerels are doing their job. It is our job to train them to act the way we want them too, chickens aren't mind readers. Some are unable to be trained, but some work out in the end.
I have never had human aggression be passed on from my chickens. That to me is like saying all pit bulls bite people... All animals in this world have the capability to have aggression towards humans, most aren't savage beasts though... Humans have fear of many animals, which to me is ridiculous since we are the top of the food chain.