Very Sad to see this kind of cruelty.
The problem is though, the moment that he gets released, "into the wild" as it is, he will be dead within a very short time.
Either by the "other gorillas" rejecting / killing him, OR, by him seeking the only company, that he has known for 30 years, and similarly dying as a result.
Jane Goodall showed this, when a young gorilla's mother died, and shortly after the young gorilla died of a broken heart !
There is NO satisfactory solution to this problem !
Only constant human supervision/care, within a carefully controlled gorilla group, MAY have some possibility of success.