I'm having the same issue, except my Roo is being a real jerk to the new girls. The two teenie boppers are 15 week old pullets, and they've been in the outdoor playpen area, "see but no touch" for a few weeks now. They still sleep inside in my *only* bathroom at night. (If you weren't all chicken people, I would be more embarrassed at how insane this sounds, but I know you all *get it*)
We're on Day Two of free range with the Big Kids (4 laying ladies, and one overly protective GIANT D-Bag Roo who attacks all things human -- all 8 months old). My blood pressure is through the roof with this! I've got hiding places set up all over the chicken yard for my sweet lil' pullets to scramble to.
The teens are doing well, integrating with the laying ladies (staying out of the way mostly), with the biggest problems coming from our hen who was formerly the lowest on the pecking order. But when our Jerk Roo decides to charge them from across the yard -- eeeek! The poor lil' babes are rightfully terrified! He attacks, and doesn't stop. I have been intervening with the hose sprayer set to STUN. I've never killed anything in my life, but if I was holding the machete instead of the hose, I think this Roo, that used to be my cuddle chick, would be a mass of bloody feathers in the yard.
Ugg. And yes, I've been trying to trying to re-home him for over 2 months, ever since his hormones kicked in. (and he sliced me down the nose) No takers. If I don't get some peace in the backyard soon, I'll have to ask the neighbor to help me send him off to the Rainbow Bridge aka Freezer Camp. :-(