It is the same concept of who "downvotes" things. Twitter is a company and it has masters just like any other person, place, or thing. FYI - http://www.latimes.com/opinion/op-ed/la-oe-deboer-yanniapoulos-jones-twitter-speech-20160722-snap-story.html may be a story you could be interested in. The LA times has it's own agenda as well, but still may be interesting.