There is a serious problem with your statement. You seem to assume that Rav Shteinman’s statement was specific to that situation, but that the exclusionary policies are otherwise acceptable. My reaction: Chas veshalom. At the very least, the dinei nefashos of allowing a child to have no yeshiva (Chazon Ish – a general psak) must be posed to a Gadol beYisroel.
Nope. I’m just saying that the P’sak given only applied in that very specific case, and I have no idea what the P’sak would be in other cases. As we agree, an individual question must be asked for each student and each yeshiva, with the Rav that is asked having intimate knowledge of exactly what the situation is, both for the school and the child in question.