I don't tolerate aggressive cock birds, whether they are aggressive towards me or towards the hens in his care. I have brahmas, so they are supposed to be docile and I expect them to be. That doesn't mean that they won't charge me when I stir up the hens, they'll charge but they know where to stop. Now if you are raising English game, then you should expect a more aggressive cock, but he still has to know who is the alpha in the flock (and it isn't him).
Yes, I'll admit that I cull aggression out. Even though I don't have aggressive cocks, when a hawk is sighted, my cock bird gets all of the girls and juveniles into the coop and then stands outside waiting for the hawk to take his chance. If there is a hawk around that is stupid enough (or hungry enough) to go after a 15 pound cock bird, I guess it would deserve what it got, but I haven't seen it yet. My cock birds' jobs are to protect the flock and fertilize eggs. They don't need to protect the flock from me and once they have learned that, they will be culled if they attack me. Fortunately, I haven't had a real problem with aggression towards me, but I have had to cull for aggression towards other chickens (especially juvenile males).
To each their own theories, of course. I have a friend on here who has Brahmas and that poor kid can't seem to catch a brake. He has bought several cockerels/cocks over the last couple years that have disappointed him so badly. They certainly were not aggressive but neither were they really interested in the hens and when one did get up enough spunk to cover a hen a few times, the shots were frequently blank and he bought from some pretty reliable folks with good reputations in the exhibition circles. Of course, they made things right but he lost two breeding/show seasons.
Turk