I am no expert, but have a flock of 14,,7 hens that are a year old, 2 hens and a coronation sussex roo who are now 5 months old, and 3 hens/1 roo that are 4 months old.
Snowy, the Coronations sussex Roo, is huge, and I mean HUGE, I know I've posted before about him, he's rather a weenie,,the older girls keep him in line and take no 'stuff' from him, they give him a peck and he's 'gone'

He's friendly with me, eats out of my hand, I don' t pick him up because frankly he's to darn heavy

, He comes running when he sees me , follows me around..
He tends to be fine with the 2 hens he was raised with (before integration),,and tends to ignore the younger bunch...He has tho been exhibiting maybe some jealousy?? I'll have one of the older hens in my lap, he will peck at my pants, 'sniveling' (best way to describe the noise he makes!), and eyeball the hen in my lap,,when I set her on the ground, he will sometimes give the hen a good peck..Usually the hen will let him have it, and he takes off,,IF he doesn't, I will intervene, as in push him off with my foot, or my hand,...he knows he better back off and he does..
So as I see it, I agree with newbie above, it's up to you on how much you think your hens should put up with..Personally, and it's just me, that type of roughness/nastiness wouldn't fly here.
Now whether you can correct it, is anyones guess, because as I read more about roos, the more I am finding, they are either nasty, or are they aren't..Not much in between..
Now mine are still young, but the minute either of them starts chasing down my girls and doing some real physical harm is unfortunately, going to be the time I rehome him..(I just don't have the guts to do him in

Diane