I myself wish that the MBTA was a little more lax. I know that birds should be protected and their conservation promoted, but I think society has improved to the point that people won't be slaughtering birds for ladies' hats like they did a century ago. Therefore, I think purposes like exhibition within zoos and conservation centers should be an exception. And you're definitely right. You don't want to be giving young children nightmares with a 5ft+ tall bird with a face like this..... I actually had a nightmare about them once. Maybe I'll tell it closer to Halloween. Yes they're super fascinating, but up close they're nightmare fuel!
I highly doubt the Migratory Bird Treaty Act is preventing zoos from holding Jabiru. The vast majority of North American birds are protected under this legislation and also found in American zoo collections. This legislation couldn't be more important today as most bird species are in the decline and many migratory songbirds are threatened by poaching.
I don't think this was posted but I found a PDF version of the Houston Zoo's master plan and it looks really interesting https://s28164.pcdn.co/files/HZI_Strategic_Plan.pdf
LA's master plan listed Quokka and pangolin. I think sometimes they put wish list species on there with the idea that maybe they can be acquired, even if it's highly unlikely. I wouldn't expect to see a giant armadillo in Houston anytime soon, probably.
And it does not mention penguins in Galapagos which are mentioned elsewhere nor does it mention the rheas acquired in recent years in the current south American exhibit. The Maned wolves have left the zoo a few years ago and it appears there are no plans to bring them back.
Strategic plans are "where we intend to be going - and how we expect to get there - as we see it today." Plans change and develop. Never read such plans as precise projections, just intentions.
Video and images showing South America's Pantanal at Houston Zoo. Houston Zoo Sneak Peek Of South America's Pantanal And Otter Exhibit | SUNNY 99.1