It's not unknown for a rooster to flog one person and not another.
I personally cull them for any human aggression as my efforts to retrain have never worked long term and I can't chance a rooster harming or killing a human child. It's great to have an animal that protects your property... Unless it's doing so with violence that is not warranted, and might cost you a lot of money and someone a lot of grief and damage.
If he was inclined to be violent, he will show that trait. It doesn't just crop up out of a truly tame mentality, rather it was always lurking. It doesn't guarantee he'll show it on you, but there is a great likelihood of him passing it onto his offspring as this is a strongly behavioral heritable pattern. Any chicken that views a human as an opponent or victim to bully, I cull. That is not a normal behavior or mentality at all. Normal chickens never even think along the lines that lead to them attacking a human.
I'm not a fan of the idea that it should become a 'who's the biggest rooster? I'm the biggest rooster!' competition because... I'm not a rooster. I'm a human. Humans must be respected whether or not they can prove to the bird they are able to manhandle it by force. The 'alpha rooster' methods of dealing with a violent rooster supposedly work for some folks though. I don't breed any bird that is confused about what species it is, or I am.
You may be willing to take the chance, personally I am not, but as I said, each to their own and best wishes with whatever your choice is.
