As Twitter CEO Jack Dorsey began to address lawmakers on Capitol Hill Wednesday morning, he made a brief aside. Holding his smartphone, from which he would read his opening statement to the Senate Select Committee on Intelligence, he first let the committee members know that he was tweeting it out. “We‘re extremely proud of helping to increase the accessibility and velocity of a simple, free and open exchange,” Dorsey said, as those words reverberated among his four million followers online.