In fact, it is absurd. Several other subspecies are also in great danger.
I don't question the importance of a breeding program for Amur Leopards (there being only around 50 left in the wild) but considering all the space and resources available in all the AZA zoos, it would seem strange for all the zoos to focus on that subspecies only and just ignore all the others that need help.
As there are viable numbers of P.p.orientalis in the States (76 according to ISIS) and either none or low numbers of the other endangered ssp., then it makes sense that they focus on what they've got.
By design really. The AZA prioritized Amur Leopards and phased out (ceased breeding) other subspecies and generic animals. Other than a handful of Persian and North Chinese, Amur was the only subspecies around and the only one with a large enough population to be viable. The most common leopard used to be generic animals with no known pedigree.