The central question seems to be the following, articulated most precisely by Mike Lee (R-UT): even if the organic search results are entirely unbiased, Google also programmatically (via "Google Universal Search", the system that organizes the overall search page) inserts specific links to other Google pages--such as Places, Maps, Shopping, or News--in very prominent positions. There are competitors for all of those…
Google is free for users and free to anyone wanting to get in their index, so they do not owe any self proclaimed competitor anything and that is the crux of it, the law is on their side, you cannot monopolize "free" and all this politicians' propaganda is waste of time and tax payer dollars..
This is why theaters were not allowed to be owned by studios, Car Dealerships by actual Car companies, etc.