I would very strongly encourage my kids to shun any child of a homosexual activist, and I would do the same with the parent. I do not want to be sued over some absurd cause for offense, and the safest path is a complete absence of interaction.
And it would be ok per rules - provided that the girls’ being at school represents a significant impediment to the learning of others... ie they’re a distraction.
Keep on kicking them out until they give up and leave.