From what I understand there are some facilities in Asia that specialise in rescued tarsiers. I don't see why the obsessive director couldn't take some ideas from there.
And I will say that I agree to a point that zoo directors are often a bit scared of what is novel; and mainly chose to invest in what they know will bring in the public. [i.e. 'ABC' animals] However in the case of many animals such space is already taken. Most zoos only have capacity for one species of tapir - two if the zoo has Baird's [assuming US] and Malayan, but then the Andes is not significant enough for most directors to consider a third. And even if one decides in favour of that there's no guarantee all others will be on the same page. And before long that's the end of that for the Woolly tapirs...
And I do think also that exclusivity can breed other things. Just like the case of the Giant Eland and all that has came of that programme.
I concede stamp collecting isn't sustainable - but I do believe that zoos could do more in regards to their collections.
Modern zoos should be focused on downsizing their overbloated collections if anything, not expanding the list of "dead end" species. If it isn't thriving already, it's wasting resources that could be going to functional populations.
I think there's a happy medium somewhere in between these too. There are plenty of species that do well in captivity, but whose populations, either due to a low founder base or other means, don't classify as "sustainable". To be sustainable, according to the AZA, there are a lot of fancy math done to show gene diversity over time, with the goal of no more than 10% diversity loss over 100 years. If we decided only to manage species already at this point, then there would be pathetically low diversity in zoo collections.
I'm going to use primates as an example because they are the taxa I am most familiar with. Based on the genetic metrics, only approximately five monkey programs are considered sustainable and would still be around if the AZA only focused on already-sustainable populations: golden lion tamarin, cottontop tamarin, common squirrel monkey, pale-faced saki, and guereza colobus (possibly one or two others, but unlikely). Surely, despite not technically being sustainable, however, there is a place in US zoos for more than five monkey species. Especially when cooperation is possible with Europe (e.g., there have been callimico and emperor tamarin imports in recent years), Asia (e.g., Japanese macaques have been imported from Japanese zoos in recent years), or new animals coming in through other means (e.g., AZA zoos regularly take in confiscated spider monkeys), it's certainly reasonable to maintain populations that aren't "technically" sustainable, but still have a reasonable chance of being successful. There's a sweet spot in between guerezas being the only Old World monkey in US zoos, and having fresh imports of proboscis monkeys, snub-nosed monkeys, and uakaris because zoos want as many cool animals as they can get.
Basically what I think is most important is for there to be enough species readily accessible for zoos to fill whatever their institutional needs are. While most zoos are going to want to exhibit primates, the needs of each zoo is going to be different, meaning there needs to be enough species available to fill what zoos are interested in having. Some zoos are going to want to exhibit an ape in their Africa section, while others will want to exhibit an ape in their Asia section- meaning it's important for both a gorilla/chimpanzee program and an orangutan program to exist. Some zoos may want gorillas in their Africa section, but others might be spatially constrained and opt for a guenon species instead. The less species that zoo organizations manage, the more difficult it will be for zoos to fill their institutional needs and existing exhibits in ways that make sense. So for each group of animals (speaking broadly, e.g., a group would be "antelope", or even "ungulates", but certainly not "duikers", there is a need to manage, in as sustainable a fashion as possible, at least one species in each size category (when applicable), and from each geographical region that zoos may exhibit that taxa in.