It's really easy to discourage this behavior. Your roo needs to stay out of your personal space and you need to see that he does. There are folks who will tell you to pick him up and carry him around, put your hand on his back and hold him to the ground, etc. I've never used those methods...some say they work, some claim they tried them with no success.
I can only tell you the method that I use and it works with 100% efficacy. You must confidently approach the bird when you enter your yard or pen and crowd his space until he moves away. When he starts to move away, relent. Try it again. Does he move away? If not, you need to force him to move away by startling him...either approach him quickly, smack a stick into the ground near him making a big noise, wait for him to relax and forget you are there and then jump towards him suddenly, etc. Anything that makes him think you are unpredictable and maybe dangerous to him. Keep him moving away from you.
If he does move away consistently, I doubt he will try this again. If he doesn't always move away from you, the above tactics will reinforce his desire to do so. All of this only takes a few minutes out of one day....I've never had a roo that I raised that would approach me aggressively. I start them out as youngsters with this method and it never really gets to the dancing, pecking, biting, flogging stage for me.
It's time to stop petting the roo and start establishing a mutual respect and distance.