This is obviously highly speculative, but Uber is a really leaky ship right now. This could be solely coincidence, but I am positing that – potentially – someone who wants increased influence at, or to increase pressure on, Uber may see opportunity here. To that end, they might be spinning parts of the narrative through their press relationships.
In other words: never let a crisis go to waste...
Top execs leaving is more easily explained. This is the time if you have skeletons in your closet, assuming the internal investigation is real, before your dirty laundry is aired in the national news. And if you see this as Uber's death knell better to bail before it tarnishes your own rep to have worked there.
Even if it's not Uber's death knell, as top exec it's probably better to bail now.
You can take your "I ran X at Uber" managerial propaganda and cash in on that for a better position. An Uber IPO probably isn't going to be life-changing amounts of money anymore for these levels of people even with the sweet deals that the hoi polloi would never get, so time to move on.
I think both things can be true at once.