It's strange how the characters from the book got to have a life of their own out side of the book. I can't think of any referent to Dumbeldor's sex life anywhere in the 7 books. I guess when you read the last book you can see dumbeldore's friend as a romantic connection or not. Non of the teachers in Hogwarst is married (or maybe they are and it isn't mentioned) Dumbeldor maybe gay just like Professor Sprout might be into SM and Lockhart might collect coins as a hobby - if it's not in the books and it doesn't contribute anything to the plot - who cares?!

Personally, I think she was feeling unpolitically correct by NOT having a gay character in the book and trying to fix it now. If she's trying to gain the support of gay organizations by coming up with this, I think - too little too late. 

There are a couple of important books like "And Tango makes three" that built a reputation and got ban by the church because their main theme was gay people and alternative families, however, I think that a random mention in an interview about something that isn't really mentioned in the book would not get the book ban by more people.