As long as they also boot out kids whose parents are cheating on their spouse or if divorced/widowed are fornicating outside of marriage, there’s no problem.
Homosexuality is worse.
Most cheaters do not advertise their sin openly and publicly, nor demand that others accept it as ‘normal.’ It is between the parties and their God. Hypocrisy is the tribute vice pays to virtue.
A homosexual couple living together as a family do publicly proclaim their living in sin, as the Church sees it. As the lesbian women must know, that is exactly the way the Catholic Church views their chosen lifestyle. By registering the children in a Catholic school these lesbian mothers are demanding that the church school accept that, and the church school is saying no.
I feel sorry for the children who did not bring any of this on themselves, but they can be well educated in another school, private or public, which is run by an organization to which homosexual behavior and lifestyles are normal, and whose teachings will not create the conflict the children would experience between home and school.
Are those people sinning openly? Are they putting forward the notion that fornication, etc., is a valid lifestyle choice? Are these people asking to be regularized? If so I agree with you to an extent.