This is a piece of artwork it's apparently "just as illegal" merely to own. (i.e. illegal under the same clause of federal law.)
Suddenly it sounds like they found some obscure law to value it at $0, and that they would not get in trouble for actually selling it. Rather than appraisers in on the heist, perhaps they should have written to the Fish and Wildlife Service to ask if they can sell the thing to pay the taxes on it. The reason they didn't do that is they didn't want to hear the answer, yes. They want their cake and to eat it, too. (Keep the work but not pay taxes).
I'm not sure I agree with the existence of this kind of tax, but the case isn't as clear as the title and first half of the article make it sound.
Even then, the government revisited the issue in 1998. Rauschenberg himself had to send a notarized statement attesting that the eagle had been killed and stuffed by one of Teddy Roosevelt’s Rough Riders long before the 1940 law went into effect. Mrs. Sonnabend was then able to retain ownership as long as the work continued to be exhibited at a public museum. The piece is on a long-term loan to the Metropolitan Museum of Art in New York, which Mr. Lerner said insures it, but the policy details are confidential.
this is respected art with a high market value. They should not have put $0 as its value.
take-home lesson: don't do that.