I found an orphan the same age a few years ago.. He was fine in my hands, but when he reached pre-adolescence my hands were suddenly terrifying. So I stopped holding him, and gave him food and cleaned his cage without moving him. If I needed him out, I let him crawl into his ball and roll around the house. I think a lot of it has to do with the fact they're wild. One generation in the hands of humans isn't nearly enough time to quell that natural fear of humans.
It's up to you if you want to release him. Personally, I never felt comfortable with the idea. I thought, his mom would have been the one to teach him how to best find food, and how to best avoid predators. I, as a human, couldn't teach him that. I didn't think my orphan stood a fighting chance back out in the wild. So I kept him.