I believe David is ok with advertising. He just doesn't want it to be the main focus of his effort. The fact that Tumblr has huge growth and Yahoo has one of the largest Ad Sales teams in the world, means that this merger will in-my-opinion be v.successful.

My bet/hope is that with more resources from Yahoo, David will pick and influence more parts of Yahoo than just Tumblr.

My guess is a twenty something riding a billion dollar wave into yahoo hq isn't going to make friends quickly. Influencing yahoo as one person might prove difficult. All the best though.