The british media are responsible for publishing what they publish, which is largely driven by public demand. The press is a cash machine, they get money from people reading or watching what they provide. We all know how it works, including Harry.
Harry, of all people, knows he is in demand and that the media will want to publish stories about him. So he has choices - stay away from the media (which is easy enough - he has a lovely house in montecito where he could tend chickens, work quietly on his charity work, and cycle his kids around the garden... etc..) or pull stunts to attract the media (such as paying a surprise visit to the UK, to attend a trial he didn't need to attend in person).
Sure, the media are responsible for what they publish, but Harry is also responsible for his own actions and he knows full well what will gain him the media attention he wants. He plays them and loves it.