I'm less concerned about Google Ad market share and more concerned with their placement of Google properties above competitors on the search results page (IE, Google Reviews over Yelp, or airline prices, etc).
Imagine: A flight search engine as a marketing gimick starts a web search engine, and shows flight results if someone searches for "flights to ...". Seems like a good thing, no? It seems like no other flight search engine would have a right to complain about unfair competition here.