Despite the fact that a gay Dumbledore still seems strange to me (I'm slowly getting used to it), I can't say that it is "wrong". It can't be wrong if JK says that it is so.
But I agree with what Morkhan said earlier (you make a great point). Just think, a whole new way to analyze Dumbledore's every move!
By the way, it makes me wonder...if JKR had intended Grindelwald to be a female character, would Dumbledore still be gay? Was Dumbledore's homosexuality just the result of JKR wanting him to fall in love with a certain type of character?