I'm still puzzled if he really is serious or not... or if it was taken out of context. Apparently, he was friends with Douglas Adams. The people I know who act that way would not even read a fantasy/sci-fi writer, let alone be good friends with one (he met his wife through Adams, so I assume that they must have been good friends).
Anyways.. of course Harry Potter isn't real. And I don't think there are even many children that truly would believe so. Or eventually, they tone it down.. like I did with some things. They'll geek out on it and maybe find inspiration from it, but it is such a non-issue. If someone was looking from the outside and thought these kids were lost or wanted to criticize or even restrict society, then ironically, I think they are more out of touch with reality than anyone. To think one's hold on reality is so much better than everyone else's that you have to "chime in" that Harry Potter is bad for kids is a fantasy in and of itself. One where you're some gallant hero of mental clarity in some pisshole of a world devoid of rationalism. Give me a break.