I'm not sure about either statement — clearly Dumbledore's gayness is neither disappointing, nor a bad example for children, but meanwhile, who exactly feels that there are limits to what gays and lesbians can do? From the point of view of the Christian Coalition's prejudices, I imagine that the lack of limits to what gay and lesbian people might do is exactly what they're worried about. The interesting thing, however, is that these are not reactions to anything actually in the books. In fact, Peter Tatchell, some might say slightly ungratefully, was moved to complain because Rowling “did not make Dumbledore's sexuality explicit in the Harry Potter books”. How exactly, I wonder would that have worked? Having him introduce, alongside the classes in Charms and Defence against the Dark Arts, one in Fisting? A sequence in which he dances in leather hotpants to A Little Respect by Erasure? A bit where he watches television, and as every new male presenter appears, the aged wizard nods knowingly and says “Course, he's one...”?
And anyway, because it is not in the books that Dumbledore bats for the other Quidditch side we should, by the values of English departments up and down the land, dismiss Rowling's pronouncement whatever. Postmodern literary theory holds it as a hard and fast rule — going back to T.S. Eliot and the New Criticism, all the way forward to Roland Barthes and the deconstructionists — that the intent of an author is absolutely irrelevant to the meaning of the text. All that matters, in deriving meaning, is the unconscious play of language and ideology: any other understanding of literature, particular any that derives directly from statements made by the author about their purpose, comes under the heading of what the 1950s critic W.K. Wimsatt called the intentional fallacy.
I suspect, however, that one of the reasons that Dumbledore's sexuality is not in the books is that it may not have been present to Rowling when she was first writing him. Because most writers do not write with everything all sorted out beforehand. For most authors, writing is an organic process, where they improvise around some basic ideas that eventually coalesce into a story, like a shape emerging from the fog. Characters, once interacting with others within this process, grow and develop in unexpected ways, and sometimes it's only at the end of it all — the point where Rowling is now, of course — that the author realises exactly who they are. My point is that I don't believe that when she created the character of the headmaster, back in the coffee shops of Edinburgh, Rowling had clearly in her mind the notion that he was gay. But I also don't believe that it's something she has just added on now, to provoke reaction, or to foster her politically correct credentials.