She's different in that the child isn't biologically hers. OTOH, the sperm donor knowingly and deliberately did his part to conceive the child. How can you not see the difference?
Of course, I wouldn't object to making her pay child support, except that then you would have a legal case for making men who aren't the biological fathers pay child support, and there's too much of that already.
And that statement, if it is indeed the basis for the court's ruling, exposes the utter hypocrisy of their earlier ruling in favor of same-sex "marriages". The earlier ruling was based on the bizarre notion that gender isn't a significant enough factor for marriage laws to take notice of. And yet, biological relation, which is inherently based on gender (it's the whole reason for gender in the first place), is still given special notice.
If I agree to adopt a child with a partner, I'm legally obligated to support the child, even if we break up. There's no biological bond, and parenthood is not all about biology. Why can't you see that there's no difference?