A Google webmaster violation is the reason this website was penalized by Google, not its controversial nature.

Natural News, a controversial alternative medicine website, according to Wikipedia, has been delisted from Google. The news site confirmed being removed from Google and recently claimed Google banned them because the site was pro-Trump.

Google has confirmed the site was not removed for its political views but rather because of a webmaster guidelines violation. A Google spokesperson told Search Engine Land:
We don't comment on individual sites, but if we find that a site violates one or more of our Webmaster Guidelines we may take manual action against it. For webmasters who have questions about their own sites, our Webmaster team provides support through platforms such as the Webmaster Forums. Once a site has remedied the problem, the webmaster can submit the site for reconsideration.
Natural News said in its post that "Google sent no warning whatsoever to our 'webmaster tools' email address on file with them," but not all penalties will receive a notification via Google Search Console. More extreme and deceptive violations will not receive such notifications.

While some are suggesting the ban is related to Google's interest in tackling the web's "fake news" problem, Google has nothing in its webmaster guidelines about such sites. Google would not penalize or delist a web site for "fake news," let alone being controversial. (Even some who dislike Natural News aren't sure it qualifies as fake news.)

Google has many penalties that can result in a site like Natural News being demoted or delisted but, as we said above, fake news is not one of them.

Postscript: John Mueller, a Webmaster Trends Analysts at Google, has now posted on Twitter saying Google did post a message about the penalty in Google Search Console. He also added a thread that the site was penalized due to sneaky mobile redirects. John said:
Hi! I work with the Google Search team. We're seeing a bit of confusion & incorrect stories circulating about what's happening here, so just to be super clear — Natural News is using a sneaky mobile redirect, which is prohibited by our webmaster guidelines (there's a bit about this kind of issue at https://webmasters.googleblog.com/2015/10/detect-and-get-rid-of-unwanted-sneaky.html ). These redirects aren't always easy to reproduce, they're sometimes in widgets or served by ad networks, and can target specific devices, browsers, or user locations. When we last checked, there was one on http://blogs. naturalnews. com/bentonite-clay-a-natural-medicine-cabinet-must-have/ . As soon as this is cleaned up, the site can submit a reconsideration request through Search Console, and once that's reviewed things will return to normal. No action has been taken based on the editorial content of this site.