We can only speculate as to why, but it seems this was a contract theft for some rich asshole. Someone who enjoys having things only he* can look at. A real sociopath, to whom the outrage involved only makes the theft sweeter. He may not even care to have it displayed, as simply being the only one who knows where it is may give him pleasure.
*I am 99% sure of gender, since this sort of theft reeks of machismo.
