Brad: Private citizens have an expectation of privacy; public figures do not. Harry's change in legal status resets his status. The Prophet can talk about the Boy-Who-Lived up through the TriWizard, but cannot impune the new Head of House Potter until such time as he does something to make him a public figure (like playing in a Quidditch match)
I have to disagree with this attitude by the press. It is my opinion that athletes and other celebrities are private citizens. The only people who should be treated as public figures are officers of publicly traded corporations, elected government officials and officials appointed by them.
Unless you have a major role in the shaping of business or government you should be treated as a private citizen. However, the above people should have lives that are completely open books with the absolute minimum amount of privacy.