It's selling paintings to plug a pension deficit.
Serious question: what kind of belief is the belief that deaccessioning (other than to buy more art) is wrong? If you follow the debates at all, it certainly feels like a moral judgment: it's repulsive, Stalinesque, beyond the pale. So why don't we see the same sort of outrage from the usual suspects when, say, a U.K. museum sells work to plug a pension deficit? If it's morally repulsive, it's morally repulsive, no matter where it happens. Right?
So complicated, the Deaccession Police Handbook.