Given that Timnit ostensibly does not know who the people who gave the feedback, nor how they did so, and elsewhere notes that she was able to see the feedback, but was told she couldn't share it because it was privileged, can you explain how you reach this conclusion instead of that "to" was a typo in a tweet and instead should have been "via" or similar.
To me it sounds like the person who submitted the feedback to HR was using privileged and confidential communication.
And yes, Jeff Dean has the authority, but the HR who got the feedback doesn't.