That’s more or less as I remembered. 309(c) provides:
“(c) Notwithstanding the provision of subsection (a) of this section, a person born, after December 23, 1952, outside the United States and out of wedlock shall be held to have acquired at birth the nationality status of his mother, if the mother had the nationality of the United States at the time of such person’s birth, and if the mother had previously been physically present in the United States or one of its outlying possessions for a continuous period of one year.”
The question is, by “nationality status,” do they mean just plain nationality? Or do they mean (i) just plain nationality when the mother is a national but not a citizen of the U.S. but (ii) nationality plus citizenship if the mother is a national and citizen of the U.S.?
If “nationality status” includes both nationality and citizenship in cases in which the mother is a U.S. citizen (who had previously resided in the U.S. for at least one uninterrupted year), then you are correct and Obama would be a U.S. citizen at birth even if born abroad if his mother was not actually married at the time.
Of course, it’s not clear whether Obama was born “out of wedlock” pursuant to the statute. Barack Obama, Sr. and Stanley Ann Dunham got married in Hawaii while Dunham was pregnant with Obama, and got divorced years later, which is evidence that Obama was not born out of wedlock. However, Barack Obama, Sr. had previously been married in Kenya, and there is no evidence that he had divorced his previous wife (who was still alive) at the time of his wedding to Dunham. That certainly complicates matters, but it seems to me that when the statute refers to “out of wedlock” births the term would not extend to births involving a mother who had been married in a legal ceremony in the U.S.
So in the event that Obama was born in Kenya, his only plausible claims to being a U.S. citizen at birth would be that (i) that his biological father was not Barack Obama, but a black U.S. citizen or U.S. national or (ii) his parents’ marriage was null and void ab initio given his father’s still valid marriage in Kenya, and the subsequent divorce was a sham.