I'm always leery of single-source reporting, will be interesting to see if there is any corroborating evidence emerging in the next few days.
"According to a bombshell revelation made in the trade magazine Gizmodo, Facebook employees known as “news curators” were ordered to exclude even wildly popular content if it was about a subject, or came from a site, that the company considered too conservative or that they simply didn’t like. They also supressed legitimately-trending stories if it was about topics they wanted to go away, like the Lois Lerner scandal, and even inserted certain content into the “trending” ticker when its popularity didn’t warrant it. According to Gizmodo’s source, this included the “Black Lives Matter” movement, which wasn’t an important enough subject to make Facebook’s trend line… until someone decided that it was."