I've got to say I'm with Moriendor all the way.
But as sad as all this reaction is, it's really no wonder if you are aware of Sapkowski's general attitude. The old man wrote the Witcher short stories, and when they became locally successful, he started dissing them all over, claiming they are not very good, even going as far as saying something like fantasy in itself cannot be literature at all, ever. He did this inspite of the short stories being quite brilliant in their own right (mixing elements of slavic folk myth, dark fantasy, anecdotes with quite contemporary economic and political ideas and observations; well, he did study economy).
Then he wrote the novels in the early 90s, and shifted the focus onto education (sort of like a fantasy Emile) and more politics. Fantasy and withcers are a backdrop in these books really, and eventually he eliminated Geralt entirely.
And then he stopped writing anything related to that particular universe after 1999, until the games started putting Sapkowski's fantasy back on the map and making it accessible for audiences worldwide. He totally and fully agreed to CDPR doing whatever the hell they wanted with this universe, since he does not want to write anything in it again, and he does not like it at all. But the money and recognition was welcome, of course.
What he says comes down to him dissing the people who adapted the feeling and message of his works very well into another media, while making entertaining games. He talks bile about adaptation in general. And he clearly has no idea what the games are about. But the money was welcome. And these guys at CRProject worshipped him, they took care of his story, they breathed new life into the world he carelessly threw away.
Am I right when I read he wants to write in that universe again, but he disregards whatever others did with his consent?! That means he completely disregards other artists while preaching about the sanctity of art.
This man is full of sh*t.