I'm confused. You're docking Polar Bear for being unsustainable but keeping Banded Palm Civet, Greater Bulldog Bat, Walrus, Harp Seal, Greater Malayan Chevrotain, Bush Dog, Fanaloka, Spot-necked Otter, etc, etc all of which have smaller populations and worse off than Polars. There's literally a single permanently held Harp Seal in the USA.
Again, confused - a large chunk of your list is not supported by the AZA so I don't get what the problem is. If your caveat for the list is it needs to be a functional population supported by the AZA, roughly two-thirds of the list should be cut, just saying.