I agree with most of this post. A few comments though.
1) Allie and Semo, the two Bottlenose Dolphins left at the zoo when the exhibit closed in 2012, did not die and that is not why the zoo stoped showing dolphins. Allie moved to the Brookfield Zoo in Chicago and is still there as far as I am aware, while Semo moved to Six Flags in California. Semo did die in 2018, however, of old age.
2) This sort of goes with number 1, but the zoo received funding from the state legislature back in 2012 or whenever to renovate the Dolphin Pool and the plans were to bring the Dolphins back after the renovation. The pool needed updates to the cieling of the tank, etc. After funding was received, the decision was made to not bring them back for a number of reasons.
@snowleopard actually sat down with Lee Ehmke, the former director of the Minnesota Zoo, and discussed the possibility of the dolphins ever returning in one of his various road trip threads (EDIT: I may be wrong about this as now I can't find it. Maybe he can tell me if I'm going nuts or not). Long story short it probably wasn't going to happen. There are only two actual zoos left in the country that still have dolphins.
3) What you see in the former dolphin exhibit is the renovations made for the monk seals. As far as I can tell all they did was put up some barriers to separate the seals from each other. I'm sure there was more involved in the renovation than that, but that is what it appears to then naked eye. I agree with you I think this is a terrible exhibit for seals, but for different reasons. I don't see much issue with the land space as seals generally only haul out on land ad not much else. They are extremely clumsy on land. For that reason, I think the amount of space is fine as they general don't move too much. I agree though it looks very unnatural and isn't great. Unfortunately, I don't think much will be done about it as all the seals are over the age of 40, I believe.
4) Finally, it is not a claim the zoo makes of them being the only ones outside of Hawaii, its a fact. They came from SeaWorld San Antonio, which was previously the only place outside of Hawaii.