As a last remark: I don't think we should be using terms like 'imprisoned' or 'locked up', which are terms the animal rights activists use to target zoos.
Who is using them exactly?
"zoos are a necessary evil"
To be fair, they are. In an ideal world, you wouldn't need zoos to act as an educational and conservational institution. And I feel like for some people this "I'm doing something for the conservation" feeling is part of their motivation to visit the zoo. Would you lure as much visitor annually even without this motivation? I don't think so.
BUT we should NOT cooperate with the anti-zoo folks in helping government make rulings against cetaceans, or any other animals, being kept in zoos. That's a decision for zoos to make, not government.
So you are saying that zoos should have their own secure shell and not come out of it when it comes to law-making? You feel like it would be better if the government would be pressured and made laws only based on opinion of people you disagree with, without offering your view? I'm glad that (at least in our country) zoo people are not that shortsighted and actually work closely with government on laws that are important for zoos.