"Credible provenance" and the Minoan larnax

Back in September 2008 the Michael C. Carlos Museum spoke about the importance of a "credible provenance" or "history of ownership" in a press statement responding to Greek claims for three items in the museum.

As far as I can see the museum has never presented the authenticated collecting history (sometimes obsoletely termed the "provenance") for the Minoan larnax in its collection.

I have read the documentation on this piece and the photographic evidence from the Becchina archive is compelling.

I am also aware that the positive identification was made by Dr Christos Tsirogiannis.

We know that the "credible" collecting history for this larnax places it in the hands of Gianfranco Becchina. Why has it taken the Michael C. Carlos Museum seven years to ignore this "credible" evidence?