The basic argument is search engine rank determines trustworthiness of a source. This influences people's opinions on politics, what they buy, what they think, etc.
This is absolutely true, and the core of their research (it seems).
But then it goes into FUD territory when talking about Google backing Hillary. Hillary and Trump have received the lion's share of attention in media, social media, and such. Google searches SHOULD show them prominently.
Worse, the article basically finishes up with a "be afraid, be very afraid" approach that rankles me. "The new hidden persuaders are bigger, bolder and badder than anything Vance Packard ever envisioned. If we choose to ignore this, we do so at our peril."
No solutions or deeper analysis. No discussions on how a search engine should rank relevancy to search terms.
I personally have no doubt that mass-media, marketing, and the internet are shapers of opinions. Bias in the media, search engines, and such is a complex topic. Not something that should boil down to "Google could make it so Hillary wins" therefore you should be afraid.