I can understand where you are coming from, but since he did live for most of his life in captivity it may be better for him if he was recaptured. He has little to no experience with the outside world and could injure himself or others if he got hit by a car or something.
Not to mention, the potential risks to native migratory birds and other owls being potentially exposed to new illnesses.
Personally I am on the fence and don’t have an opinion either way, both sides have good arguments, but I just wanted to give the other perspective to it as well. =)