I’m still not sure how old that rooster/cockerel is. It sounds like he is still more cockerel than rooster. He is trying to assert his dominance over them but the older hens are just not ready to acknowledge that young whippersnapper as the boss of them. For a cockerel in a flock of hens it’s more about flock dominance than fertilizing the eggs. Cockerels can often be jerks.
A mature rooster should not try to mate a hen that is not laying, whether broody, molting, or pullets too young to lay. Laying hens usually have bright red combs and maybe some other signs that the rooster interprets as the eggs need to be fertilized. He’s mature enough to see that.
The mating act is about dominance, the one on bottom is accepting the dominance of the one on top, either willingly or by force. A mature rooster is so self-confident, glorious, and magnificent that the hen generally don’t mind squatting for him. An immature cockerel is none of those things. His hormones are telling him to dominate the flock but those hens won’t squat for him. So he resorts to pecking and force.
I’ve been through this a few times. If he is not injuring the hens I just let them go, they will eventually work it out. If it bothers you or there is injury, there is nothing wrong with locking him up (with or without the pullets) where he cannot get to the older ones until he matures more. Maybe until spring and the older hens start to lay. They should be more receptive to a male when they are laying anyway.
The only reason you need a rooster around is if you want fertile eggs. Everything is just personal preference. If you don’t want fertile eggs and he is disrupting the flock or causing you anguish, get rid of him.
Do roosters not mate hens when they're molting?
