Google claims Uber execs were meeting with Levandowski long before he left Google, that his entire leaving Google to form Otto (which would be soon bought by Uber) was planned alongside Uber.
Now Uber is saying "Hey, we didn't know anything about that, but I think you guys really should go after this guy here". Somehow, given Uber's reputation as a moral and ethical company, I am not shocked by this development.
Edit: And another thought- why wouldn't Levandowski now walk into the justice department and say "Give me immunity, and I'll give you all the evidence that Uber was in on this plan from the start". If Uber are going to screw him over, why wouldn't he return the favour?