"The Potter books in general are a prolonged argument for tolerance,"
I find with all things Harry Potter, that I really enjoy it, until I start thinking, and then I get irritated. It was the same with Rowling's recent announcement about Dumbledore's sexuality.
At first I thought "awesome! positive gay characters in children's literature!"
And then I thought 4 things.
"He is my character. He is what he is and I have the right to say what I say about him."
Once your book is published, it doesn't belong to you anymore. It belongs to your readers. Let THEM tell YOU what happens next, not the other round.
"If I'd known it would make you so happy, I would have announced it years ago!"
No. You should have announced it years ago anyway. You should have put it in the books. You are probably the most influential human being in the world for young people. You have more power to influence young people's attitudes than the United Nations, Sesame Street and their parents combined. You had an opportunity to present them with a positive gay role model, and you chose not to, I assume, because you were scared of the reaction from the religious right.
[Rowling] didn't feel the need to be explicit about Dumbledore's sexual preferences because she wanted to focus on character development.
I'm going to skip over the fact that many gay people might find that sentence deeply offensive.
Dumbledore was brave. Dumbledore liked to stick it to the Man (no pun intended). Dumbledore was never afraid to tell anyone his opinion, no matter how powerful or dangerous they were.
Except no one in the Harry Potter world knew he was gay. Not Harry, or anyone else that we know of. So he was in the closet.
So if a man as open and brave as Dumbledore felt he needed to keep his sexuality a secret - exactly what kind of a world is the Potterverse? How homophobic must the world be for Dumbledore to conceal such an important part of his identity? That's not a "positive message" at all, or a "prolonged argument for tolerance". It's sad and regressive and scary.
Seriously. Like Rita Skeeter wouldn't have known and put it in her book.