We also don't know who is really what, which makes it even more complicated. Even when someone identifies as straight they may turn out to have been closeted. Skin color isn't the same thing, but anyway... this is far beyond the question of queer theater by queer people.
And, if I may ask, what are we using as a definition of "gay?" What if an actor who we assume is straight goes and sleeps with a couple of men before auditioning for a "gay role?" Who are we, as gay men, to say he can't do the role?
I'm also of the opinion that one's sexuality is no one else's business. If they want to broadcast it, that's their prerogative. So yeah, if we're saying that only gay men can play gay men onstage, doesn't that mean, by definition, that they have to be out?