I don't think this is particularly Harry-specific:
Drug use has always, always been an entirely different affair when practiced by the wealthy. How many technically foreign investment bankers have closed how many totally coked up deals on Wallstreet, do you think? I'm not even going to ask about celebs!
That said, I hope Harry wins this case. Not because I care about Harry specifically, but because I personally would hate to see a precedent that allows an ultra-conservative US based organisation that's part of an ideological network to access people's data / documents. They'll use it to argue for access to abortion records next. Or other "morally reprehensible" (from their POV) stuff.