It's funny now divisive Lang Lang is with classical people. The Reddit classical threads are full of people outraged that they had him play this and declare him the worst possible person in the world to debut a Chopin piece.
They also have to forge the found document, or be in cahoots with someone that can do it. And have access to surreptitiously insert it into the document collection it was found in.
A great execution too from Lang Lang.