The way I understand it is a cockerel with any human aggression tendencies will/can become human aggressive due to multiple factors. One is when they lose all respect for you and decide to dominate, which often happens when they're held and coddled (of course this isn't all). Another way is when...
This has been my experience, at least until they reach maturity. I don't do completely hands off, but I don't hold them a lot once I realize I have a cockerel. Half of the boys from my first year are jerks, oddly enough including a white Silkie, but ALL of the boys that I've added in the time...