Paczkowski outlines a Google report which argues that the discretion of Google in ordering and selecting search results is akin to an editor at a magazine. In this line of thought, the act of curating and ordering is protected as free speech in much the same was as the work of an editor.
“Search engines select and sort the results in a way that is aimed at giving users what the search engine companies see as the most helpful and useful information. In this respect, each search engine’s editorial judgment is much like many other familiar editorial judgments.”
-Eugene Volokh, author of the report FIRST AMENDMENT PROTECTION FOR SEARCH ENGINE SEARCH RESULTS
Essentially this report justifies the current Google practice of featuring their in-house resources, such as Google+ and YouTube, as primary search results. If Google wishes to curate their own content for user search results, Volokh argues they have every right under the First Amendment.