That may or may not matter. It's not that he, BHO Jr, was a British Citizen at birth, but rather that his father was not a US citizen. If BHO Sr was listed on the original BC as the father, even if they weren't married, he's legally the father. Of course because he was, under this assumption, born in the US, little BHO was a citizen at birth, but likely not natural born. Same if he was born outside the US, he'd be a citizen, if his parents weren't legally married, but not natural born, because it's a statue that makes him a citizen in that case. If born outside the US, and parents married, the statue makes him not a citizen at all, because Stanley Ann failed the US residency test, which as you know, is different if the mother is married than if she is not.
The argument based on his dad’s citizenship is different than BO’s citizenship. Donofrio is trying to argue BO’s British citizenship.
I feel with great certainty that a court in the 21st century is going to take into account the fact that a woman could get knocked up by a foreigner and have that foreigner abandon her and not penalize the child if born in the US - whether they would differentiate between whether the alien married her or not is another thing.
As for claims about what is and is not an NBC, no one here knows other than the strictest interpretation. In the 21st century, there is a great possibility they will include situations that are not the strictest interpretation.