That's a pretty good reason then, I wasn't aware of Toledo's repeated issues with keeping Masai.
While I do eco your frustration with the slow pace of the Masai phase-in and with the AZA for deciding to hybridize the other populations in the first place, the sad reality is that
@Echobeast is correct in that there are far too few pure Masai and too slow of breeding to replace the generic giraffe population the way we would like to. The situation in America is quite different to that of Europe, where cross-breeds are still bred in many zoos meanwhile there are four pure giraffe programs, some of which are unable to grow and others suffering from overpopulation due to a lack of available holders. Sadly, I would be very surprised if we ever see American zoos import giraffes from overseas to initiate a new program. Apart from the sheer cost of importing a sustainable founding population, the US has their ever annoying importation laws when it comes to ruminants that would make such an endeavor insanely costly and difficult.
~Thylo