As their request? Sounds like they don't like NVidia generating income off of their games. I'm not sure how xCloud shares its revenue.
Nvidia is generating revenue off people paying for virtual machines. You quite literally have to own the games to play them. You can't purchase them through a NVIDIA store that shares revenue on every purchase.
Additionally, the Blizzard client states you can't play the games through streaming services, so while I doubt it is a "we want a cut of your revenue" kind of thing, it is probably more so wanting to ensure the legality of it and or ensuring the integrity of the games themselves.