Which is more likely to start a controversy and trigger the law? A teacher saying that she and her husband went to a Christmas parade or a woman saying her and her wife went to a Pride parade?
Just because a thing can be expressed in different words does not mean everyone always has the awareness to choose words that are politically desirable at every single point of their lives - especially when you are trying to teach children to use precise language (family implies a group of more than two people), and when identical similar language is perfectly ok if you have the right set of genitalia.
I am not arguing for teaching toddlers about homosexual BDSM culture here. I just think that particular law is overreaching its goals, possibly to stroke the egos of religious zealots.