I'm just glad I'm not the one that has to ultimately decide. That's one togh call.
I lean toward release. But, it's been postulated that survival for this animal in the wild is not too optomistic. Flat out killing the animal seems to serve no purpose. Continuing the shows just seems extremely disrespectful of the human life (lives) lost.
I guess that's why they're called "killer" whales. Who'd pay money to see Absolutlely-no-danger whales? I think the root of your question is the debate: Should animals can be entertainment? I say, no. However, I hypocritically pay money to go to zoos and take my kids there. I want them to learn, experience the beauty of nature, and have the safety of fences. But, zoos and animal shows are different things.
So, for me the real question is the not the fate of this animal. But, rather, the future of animal expoitation for entertainment. Or, at least, where does entertainment and education cross the line into exploitation and possibly even abuse?