Is this the sexual equivalent of the one-drop rule?

Leading with "The dead keep getting outed:" Andrew Sullivan quotes a New York Times article speaking of an "early homosexual relationship with a white businessman." This comes after Andrew just had to walk back his absolute certainty that Gandhi was gay and take the position that we'll probably never know his sexual orientation.

The problem, as I see it, is first that Andrew doesn't really believe in male bisexuality, and second that he always favors evidence of homosexuality over evidence of heterosexuality (at least in famous people). In Malcolm's case, his six children (two of which, twins, were posthumous) were a little too much for Andrew (possibly in a more cautious mood after the Gandhi experience), but he still led with "outing" and held it open. Come on, the sexual relationship, if it happened, was when he was young with someone who was apparently powerful (meaning the relationship could have been a power relationship, or done for mercenary reasons, etc.). It is utterly unreasonable, given the weight of evidence against his being gay, to think it's really an open question. Unless one bit of gayness makes you gay as one drop of African blood made you black back in the era of Jim Crow (obviously with the reverse intent).