Rescued animals that can't be released are one thing. Endangered species are a completely different ballgame, because then you're more likely than not talking about a breeding program. (Bottlenose dolphins aren't listed as endangered.)
Breeding gets to be a thorny issue, because source populations and genetics become important points of discussion -- especially with marine mammals. SeaWorld used to make claims that they could breed animals (yes, including orcas) to reintroduce into the wild, but it doesn't work if the pairing is such that the sire and the dam are from populations that wouldn't interbreed in the wild. When you see animals (any animals!) on SSP's in zoos and aquaria, there is extensive documentation and tracking behind the scenes to make sure that animals released from captive breeding aren't introducing genes that wouldn't have been in the receiving population to begin with. That's part of what makes that work so amazing; on the other hand, it shows pretty clearly if there's a claim beyond the animals' true history. Just saying, "Well, maybe they would meet," wouldn't cut it.