I wouldn't let them preach, thought no one is perfect, the Bible does point out that a preacher should not have marriage problems and relationship problems.
As to targeting people (to invite to church) there is no reason to target demographics specifically. There is only the need to let those without know what we have to offer. Love, truth, money, food, etc..
The problem is the fact that a homosexual may come to church wanting to be loved, then that homosexual will get angry if we talk about sin. Those are the types of people that should be disfellowshipped or asked to leave.
Everyone wants to be loved, including homosexuals but that does not justify ignorance and arrogance when asked to accept ones sinfullness.
P.S. unrelated... Gay acts have a greater chance of spreading HIV. Greater chance of bleeding etc, then there is the sexual revolution aspects of being gay. People who worship sex tend to do stupid things sexually! No stereotypes here as a Christian I deal with facts, just trying not to be graphic! Please learn something before responding.
Jobe, David (prophets of old), Peter, James, Luke Timothy many of these apostles yes they too, had troubles and marriage problems, God Loved them as the same, and of course counselled them through revelation or appeared to them as the old testament does quote.