You assume that they can be kept. But if they have never been kept, then this is merely an individual assumption. I'm just employing basic logic: if there is no husbandry of species X, then there must be reasons why this is the case. If you can outrule common, apparent factors like bureaucracy, population size, availability, the lack of public interest that you've mentioned, nutritional / behavioral specialists, (...) etc., then it is safe to conclude that there are inherent limiting factors, like the lifestyle of the species not agreeing with the conditions in captivity. And I think that this is the case here. So the general absence of PMOWs in captivity is in my books an indicator that their husbandry demands have not been completely met - which is supported by the aforementioned ZSL publication.
Again, I agree that the PMOW is likely not viable in captivity, especially do to the relatively recent ZSL report.
Of course factors such as legal complications, conservation status, public/institutional interest, etc. are all valid, but none of those inherently imply it cannot be done. Nutritional and behavioral specialties can imply it cannot be done, however, as is the case with many an animal. Yet we have specialty species such as pangolin which historically could not be kept but have been significantly more successful in recent years, though there is still much room for improvement. Failure in the past cannot be equated to failure in the present, though fear of which will be another potential factor. Of course, there is also the one factor being ignored here which is the most common of all: it has not been done, simply because no one has tried. Most animals fall under this category, and for no other reason other than simply no one's kept them (yet). Yes I do assume that animals whose close relatives, and I do mean within the same genus, have been kept very successfully can probably also be kept successfully. This is, of course, not always the case, but more often than not it will be. Three out of the four
Leontopithecus have successful captive breeding programs, so why hasn't ever
caissara been kept? The simple answer is it probably could be, but no one's ever tried it. Same goes for the Tapanuli Orangutan, as well as the various endangered kangaroo-rat species,
Eleutherodactylus species, etc. Sometimes, the limiting factor is only as simple as "no one's done it" and that's the only reason. Something never being attempted ≠ not capable of being kept.
You're right, though, it is an assumption (however well informed) that it can be done, but if I can't assume it can be done when there's never been a modern attempt then you cannot assume it can't be done when there's never been a modern attempt
Schrödinger's husbandry, if you will
~Thylo
But have your last word, I'm not going to keep going in circles over this.
Or was that just another *dramatic music" assumption? 