I think you missed the part that states that the biological father is not a citizen, just merely same-sex married to the naturalized US citizen. They appear to have deliberately used an innocent child to try to force a change to US law.
Actually, according to the article they are both USCs, but the bio dad did not meet the five year residency requirement, so they are trying to claim it via “two USC parents”.
Can his spouse claim him on his taxes?