It's hard to know why someone would sell. But, from Google's perspective, buyout or not depends on the anticipating settlement cost. I don't see the need of a buyout if the settlement is under $500 million. On the other hand, if it's in the $1+ billion range like Tivo predicted, then Google buying Tivo would make a lot more sense.
While Google waits to see what damages they might been on the hook for TIVO could be talking to others also intersted. The best case would be another company makes an offer for TIVO putting Google on the defense to crap or get off the pot.