(Reply to old post.)

That would allow a "getting out the vote in the white sector of town" sort of abuse, where either

1. Someone deliberately invites group X because it's correlated with group Y, which they really want to invite but which they're not supposed to, or
2. Someone invites group X without any deliberate intentions of doing so to increase the population of Y, but they happen to be a Y themselves and memetic evolution has led Y to adopt that as a strategy for spreading.