To my understanding this is only true for some parenting rights in some states - not nationally!
Based on that, I consider it erroneous to casually dismiss a valid concern as a red herring.
Do you have any proof that this is the case? Your the first person I've heard to claim as such, if not then yes it's a red herring.
Invalid comparisons to things such as slavery and capital punishment, were amongst some of the more outlandish whoppers catching my eye.
It's a counter argument to claims that we shouldn't change the definition because it's tradition and that we never would have progressed as a society if we weren't willing to make those changes.