It does perhaps say that, but it also perhaps says that the parents and administration of that school are less concerned about the inevitable (or possible, if you prefer) negative influence they will have on the other children.
It’s a balance. The flip side is yeshivos who kick out kids all the time–essentially guaranteeing they will go off the derech–on the safeik that they might negatively influence someone.
It’s very selfish attitude. You might ask what tenets of chareidi’ism provide that you are supposed to value any amount of risk to your own over any amount of damage to another. I’m not aware of any teaching in the Torah like that, so it must come from outside influences.