The advice I've given is based on the information given by the OP. There at least two children involved. This dominant and submissive stuff is just so, well, outdated and clumsy.
Yes you can scare a rooster into thinking twice about launching an attack. You can do this with most animals. Hopefully as we become more aware of why chickens behave the way they do such attitudes will fade away.
I've seen dogs cowering in a corner because the owner has used similar tactics to make the dog submissive.
If this was a single keeper the article form Beekissed may have possibilities. But this seems to be a case of family involvement and the safety of the children needs to be the priority, not the training of the cockerel. Whatever method one chooses, and there is no shortage of advice, that method takes time and consistency. In this case it reads as if time has run out and the cockerel is already tried to launch an attack on the OP's son. I just can't see family training sessions being realistic.
I've got roosters/cockerels here; 5 atm and over the years I've lost count. I've never had to try to intimidate/dominate, beat with a stick, hang upside down, or any of the other rather unpleasant so called 'rooster' training programs.