My guinea fowl will attack and chase off any strange bird that comes onto my property.
They are great with my flock of chickens, any young the chickens have, and my fancy pigeons. But, if a new chickens strays in, or a wild pigeon lands to feed with my fancy pigeons.. the guinea fowl spot it straight away and launch the attack.
I was very surprised how they can recognize trespassing birds.. but the guinea fowl all look identical to me.. so if they can tell each other apart it must be really easy for them to spot new birds.. chicken or pigeon.
I had a think about what the OP should do. If it was me I would let the rooster into your hens coop and keep him with your hens. After a week or so let them all out and he should think you place is his new home and stay on your property with your hens.
If you neighbor misses him.. and asks if you have seen him, tell them that he has moved in with your lot and changed home. They might just let you keep him, or, if they want him back you can tell them they must build a pen for him, otherwise he will just run away from their home to be back with your hens.
That way the problem is now your neighbours and not yours... and you won't have to worry about the rooster taking hens away to live on your neighbours property, as he will see you place as his home.