If you have extra boys and don't need him, I'd cull. If you do want to keep him, I had success with a broken legged hen a few months back--I moved her to her own little enclosure (a spare Rubbermaid) and set up water, food, and calcium where she should reach all by just stretching out her neck. She pretty quickly figured out how to hop around on the leg, and it fully healed (with a limp) by about 6 weeks, and I reintroduced her to the flock, where she did great. So trying that is definitely an option! I'm not sure if it would functionally work for a roo, though, since a limp might impact their ability to mount the hens.
Edit: Noticed that you mentioned it had broken the skin--make sure to put on plain Neosporin (without pain meds, they're toxic to birds) if you do try to heal him! But that's definitely going to complicate things. My hen has a closed wound, so I didn't have to deal with infection risk. If he were mine I'd just cull, but I have an extra roo in the wings ready to take over his duties.
