Could be simply that the banker who comissioned the portrait didn't pay up so the work was never delivered.
There are many who believe the NYT, Washington Post, and the Democrat Party talking points too.
Actually, the author supports Dan Brown's assertion: the artwork is described accurately, but the interpretation disagrees with convention. That was exactly what Brown set out to do!
Anybody else listen to The Jesus Christ Show last Sunday?
It was amazing the way Jesus blew the DaVinci Code to smithereens !!!
http://www.kfi640.com/pages/streaming.html at 8 to 11 AMCT