The thing is.... JK Rowling is no longer the definitive 'expert' on her characters. Once they are out there, (no pun intended), then they are open to interpretation. If she really wants the word to know Dumbledore is gay, then she should have put it in the book in the first place.
And really, other than her own backstory for her own personal use, what difference does it make? I think it goes to show you that JK Rowling thinks that just because she is a billionaire from her books that she is actually a great writer. I think she thinks a bit too much of herself as a writer. A marketing genius, yes.
I feel so sorry for the father in the Sun today (I only read it because it was on the table where I ate lunch) who got Dumbledore tattooed on his back for his 4 kids. Now he can't go anywhere without being teased.

So, how do we all feel about Gandalf? Afterall, he was played by a queen in the movies!!!