That's not what she said at all. She 'outed' Dumbledore in an offhand way by saying that he 'loved' Grindenwald when he was a young man. I make a clear distinction between homosexual orientation and activity, and don't use the word 'gay' to describe homosexuals because it is more a POLITICAL term than one identifying a sexual inclination.
Since there is no homosexual activity in the Harry Potter books, I prefer to consider Dumbledore as asexual, as are all the teachers at the school.
http://www.hindustantimes.com/StoryPage/StoryPage.aspx?id=578de009-03fd-46df-8722-cef9de657d32&&Headline=Harry+Potter+author+'outs'+Dumbledore
Her words, not mine.