Also, sponsoring Adblock is changing the market conditions. Adblock can use the money provided by Google to make sure any non-Google ad is blocked more efficiently. They can also advertise their addon better, provide better support, etc. Google sponsoring Adblock directly affects Adblock's ability to block the adverts of other companies around the world.
To me, this is changing market conditions in the same way as my AT&T example. Google paying AT&T enough money for priority could allow AT&T to build new 'Google only' cables that Bing couldn't use. Google paying Adblock enough money to whitelist their ads could allow Adblock to grow enough to block Bing ads on a large percentage of user's browsers. Very, very similar.