- Google's MADA agreement forbids OEMs from making anything but Google Now/Voice Search the default digital assistant on Android devices with Google Play.
- Google is telling it's hardware partners for Google Home and Google Cast they're forbidden from supporting competing digital assistants.
So, having Viv as a second digital assistant which isn't default on their own devices and doesn't support any of the products Google's does, doesn't make a lot of sense. But if they need something compelling on Tizen to launch an exodus from Google's platform, where the Pixel has just been declared to get a ton of exclusive features they won't have access to... well, that'd be a reason for Samsung to buy Viv.