The difference is in those cases where the person in question announces their homosexuality. Just as with the homosexuals in the Boy Scouts and in the military, once you announce your homosexuality, you are, in fact, announcing that of the two issues (leadership or homosexuality) homosexuality (and public acceptance of it) is the priority.
It’s not the predilection to being homosexual that’s the sin, it’s acting on it. We all have sinful natures. I, myself, am a non-practicing adulterer. I’m sure I would love to cheat on my wife with other women. But as a Christian I would not do such a thing because I know it’s against God’s law as well as knowing it would hurt my wife and kids.