Uber could really play that to their advantage: "Your Honor, Google is just trying to soften us up because they don't get their way in the boardroom..."
Having two roles in a lawsuit is a very dangerous thing, no matter how much their ex employee is at fault here they could easily make a lot of smoke out of that.
How does that actually play out? Google Ventures and Google's self-driving car were both "Google" when that investment was made, but now Waymo and GV are ostensibly separate entities. Is Alphabet suing Uber, or is Waymo suing Uber?
Waymo is a wholly-owned subsidiary; there's not going to be much distinction here. Not that I agree with the parent poster: the equity ownership is unlikely to be relevant to the case. People have successfully sued their own corporations and other bizarre legal actions.
Having two roles in a lawsuit is a very dangerous thing, no matter how much their ex employee is at fault here they could easily make a lot of smoke out of that.