Without having learned street smarts he won't survive in the wild. Pigeons are domesticated animals and even when raised wild live short and hard lives. They survive by breeding a lot to offset the losses. I would keep it as a pet. Letting a single bird fly outdoors wirhout a flock is very risky as he can be targeted by a hawk. They adapt well as indoor pets if its what they know.
I'm going to ask one of my co-workers today about commissioning her husband for an outdoor aviary (since he does some really nice woodworking). I already have something in mind for it, but need to draw up the plans. 