Minifingers, inequality of education provision happens within the state sector too, and it's not usually because of the education being offered, it's because different schools have different challenges according to their intake, and therefore have differing priorities.
But as education doesn't begin and end at the school gates, there will always be equality of education. I take the point that what the state provides should be the same for everyone, but the fact is that it's not, and until that's addressed it's pointless attacking private schools for the reason that they give something different.
I believe that schools are communities too, but I don't believe that taking the most educated and the most privileged away does anything to the others. Either way, the children from those families aren't there to serve the children from the families that aren't educated and aren't privileged. They go to school to learn, not as a favour to other people.
But if you do believe that the most privileged, educated etc being taken away from one school is harmful then you need to state what the benefit would be for those children you want to bring back. Where's the benefit to them? They have to have something to gain when they are being denied the thing they already had, because unless it works both ways, then you are simply saying you want to penalise people for doing well in life, and that's just wrong.
The majority of the country's population does not exist for the sole purpose of making the lives of the disadvantaged and disengaged better. They have their own lives to live.