Buffett is selling off Moody's while Gates Foundation sells off Berkshire B's

The NYT article on big three troubled rating agencies with as much as 85 % of market share (moat!)
Just wondering -  if you (Berkshire) own 20 % of something as big as you house, would you know what is going on with it before other people in a world? If you have suspected cracks - quietly sell it.
Link to my older post on Berkshire proposed B-shares 50:1 split can possibly explain why ONLY Gates Foundation is steady selling off their own Berkshire Hathaway Class B shares.