Unclear as to the intent of the word "Heist" in the title. Seems they are paying top dollar if not more for collections sometimes not even authenticating them. As long as they make everything available to the public and to researchers, I don't see anything wrong with it. Also unclear on why this is a two-part story. Is there some big shoe to drop? Trying to avoid the impression that the author is not terribly fond of…
The idea cited in a reply that such purchases are funding ISIS (chilling to say the least) kind of implies that ISIS (or a stooge acting on their behalf) is the seller so a trace on the transaction should lead investigators to their door where the items can be confiscated and returned to the museum or public collection from which they were plundered.
I'm probably being too naive about how all this works. But I certainly understand the article much better now thanks to the informative replies.