Supporting looters is a "complex moral argument?"
Once again, I didn't say I supported either side.
But yes, a significant portion of the antiquities found in museums are looted. Many were looted by governments. This isn't new to ISIS although with them it presents an even more difficult dilemma because they are known to destroy irreplaceable artifacts. Looting is obviously to be discouraged for many reasons but foremost among them is because the looted items (many being "stolen" from the ground in unauthorized "digs") lose their provenance and much of what can be learned is lost. On the other hand, if the government lacks the funds to do real science, and the items are already dug up, is it better to learn what is to be learned or to lose that information forever? Much science can still be done and much can still be learned from artifacts even without proper provenance. Of course, even more than provenance is lost. What if that artifact could have led to even greater discoveries, and those are now lost because we don't know where it was dug up? What if the looters, being more interested in saleable items, threw away things that were, scientifically, even more valuable because they didn't "look" like anything to an untrained eye? In the last couple years alone huge discoveries have been made from tiny potsherds which pushed back the origins of several languages back in time by thousands of years.
For all these reasons, and a host of others, most museums have a policy against purchasing items known to be looted, but the fact is, the market is huge and its not going away. So many things are looted or are in a "grey" area that museums still buy them and even the best museums sometime violate their own policies to acquire pieces of particular historic significance simply in order to preserve them. And if the museum acquires a fantastic artifact and they learn something historically earth-shattering, the possibility is that reputable journals and magazines won't publish it because the provenance of the artifact is questionable.
Even in ISIS controlled territories, there are many grey areas. Before the Gulf War, some museum curators took prized holdings home and buried them. Others were deliberately smuggled out of the country. This was done by reputable agents in order to preserve them. Before the Arab Spring artifacts from the Egyptian national museum were placed "on loan" without proper approval (technically looted) to museums abroad to protect them. What's the right thing to do?
ISIS is known to destroy all manner of historic arifacts, especially any that have any religious significance whatsoever (to any religion whatsoever). If items are stolen before ISIS is able to destroy them, is smuggling them out of ISIS controlled territories before they can be destroyed a moral good because they were saved, or morally bad because they were smuggled illegally. Once again, this become less ambiguous, but still academically troublesome, if ISIS itself is raising funds by selling this stuff. I don't think anyone would support the purchase of such items if it knowingly supported ISIS, but academics would still cringe at the thought of these artifacts (history itself) being destroyed. I would be very interested to read the report of the government's investigation into the Hobby Lobby artifacts. One report that I saw said that at least one of the agents that acquired them was an Israeli. Somehow I don't see ISIS selling to an Israeli national, or an Israeli (even one selling morally questionable artifacts) being "in bed" with ISIS looters. I'm curious where these items came from and how they found their way here.
So yes, in the world of archaeology, looting is a "complex moral argument" that professional, amateur, and even armchair archaeologists have to deal with every day and it is discussed regularly, and at length, in professional magazines and journals.
Yes looting is wrong.
Destroying historically significant artifacts is wrong.
Assuming ISIS is not a part of the equation...
What if someone came to you and you had to choose one?
What if you had spent your entire life studying the type of artifacts in question and you knew that they were, academically and in terms of dollars, utterly priceless?
Which would you choose?