So?
Really, So?
Theu knew beforehand their lifestyle was against the rules the school was run by, and they chose to ignore those rules.
By ignoring the rules of the school they decided they were better then the school.
The school decided they weren't.
Catholic schools don't make such rules about who might attend.
I have no problem with the school's right to kick out anyone they want.
I support the school's right to expel anyone they choose. I also applaud the couple for not making this into a lawsuit or going to the press to complain.